JPH086424A - Fixing device for image forming device - Google Patents

Abstract

PURPOSE:To make the coating quantity of a releasing agent uniform over the entire lengths of the front and rear sides of a web by making the abutting pressure and (or) abutting width of the web on a surface to be clean at the time of cleaning by the second surface of the web different from that at the time of cleaning by the first surface. CONSTITUTION:The releasing agent exuding from the web 12 and sticking to a fixing roller 1 is set not to make a difference in the cleaning between the first and second surfaces by a means for making the energizing work of the spring 11' of a web roller 10' setting the abutting pressure on the second surface at the time of cleaning by the second surface of the web greater than that of the spring 11 of a web roller 10 at the time of cleaning by the first surface (the spring constant is made high and the displacement of the spring is increased) or the web roller 10' harder than the web roller 10 (a contact area is made small and the abutting pressure is made high), etc. In such a way, the second surface abutting pressure P2 is alpha (alpha>1) times higher than the first surface abutting pressure P1, so that the discharge quantity of the releasing agent on both surfaces is made uniform.

Description

Detailed Description of the Invention

[0001]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine and a printer.
In particular, it relates to the fixing device.

[0002]

2. Description of the Related Art As an image fixing device in the above-mentioned known image forming apparatus, a pressure contact nip between a fixing roller having a heat source and heated to a constant temperature, and an elastic pressure roller in pressure contact with the fixing roller. Widely used is a structure in which a transfer material that electrostatically carries a toner image is passed through a portion to be heated and pressed to melt and fix the toner on the transfer material to the transfer material.

In this type of fixing device, when the transfer material passes through the nip portion, the toner directly contacts the fixing roller, so that a part of the toner adheres to the surface of the roller, and this also adheres to the pressure roller. There is a possibility that an offset phenomenon occurs in which the toner adheres to the front and back surfaces of the transfer material that subsequently arrives at the nip portion, resulting in deterioration of image quality.

In order to deal with such a problem, it has been proposed to prevent the occurrence of the offset phenomenon by covering the surface of the fixing roller with a fluorine-based resin film or coating the surface with a releasing agent such as silicone oil. However, the actual situation is that such means alone cannot sufficiently prevent the offset phenomenon.

Therefore, a method of contacting and rotating a cleaning brush with a fixing roller, a method of contacting and rubbing a web impregnated with a release agent with the fixing roller to remove the toner adhering to the roller are proposed. What is being done is well known.

As the above web cleaning means, in order to clean the fixing roller, the web and the cleaning roller are simultaneously brought into contact with the fixing roller, and one surface of the web contacts the fixing roller and the other surface contacts the cleaning roller. It has been proposed that the cleaning function be improved by bringing them into contact with each other (Japanese Utility Model Publication No. 59-104159).
Further, in order to make effective use of the web, a structure in which the front surface of the web is used and the unused back surface is reused is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-290758.

An outline of an example of a known fixing device in which one side of the web is used and then the back side is brought into contact with a fixing roller to be reused will be described. FIG. 9 is a side view schematically showing the structure of such a fixing device. The fixing roller 101 and the pressure roller 102 are provided inside to receive the transfer material which has been transferred at a transfer portion (not shown). Fixing device body 1 for fixing
A web unit 114, to which a long cleaning web is attached, is detachably attached to the upper part of 15.

The transfer material S carrying the toner image T passes through the guide 3 and the pressure nip portion between the fixing roller 101 and the pressure roller 102, which house the heating source 6, and the heat and pressure at this time It is assumed that the toner image is fixed on the transfer material and then discharged to the outside of the machine. Reference numeral 105 in the drawing denotes a separation claw that prevents the transfer material from adhering and running along the fixing roller after fixing, and reference numeral 104 is a thermistor for detecting the temperature of the fixing roller.

As shown in the figure, the web unit 114 disposed above the fixing device main body 115 has a web 1
Winding and unwinding shafts 108 and 109 for mounting 12
The web 112 wound around the shaft 108 is fixed to the shaft 109 via the web rollers 110 and 110 ′ in the illustrated case.

As shown in the figure, when the web unit 114 is mounted on the main body 115, the web roller 110 is positioned on the fixing roller side, and the spring 111 mounted on the shaft supporting the web roller causes the web roller 110 to intervene. 112
Is pressed against the fixing roller 101. Therefore, by sequentially winding the web around the shaft 109 with an appropriate drive source, the web portion contacting the fixing roller 101 by the web roller 110 slides and cleans the roller surface.

The web unit 114 having such a structure has notch holes 107a and 107b formed at appropriate positions on the side walls thereof, and one notch hole 1 is formed at the mounting position shown in the drawing.
When the web unit is attached to the main body of 07a, the dowel 113 is provided at a position on the main body side corresponding to the cutout hole 107a, so that both are engaged and the web unit 114 is set at a fixed position on the main body 115. I shall.

As described above, when the web 112 is completely wound around the shaft 109, the web unit 114 is removed from the main body 115 and turned upside down so that the notch hole 107b is located at a position corresponding to the dowel 113 on the main body side. Therefore, the web unit 114 is set on the main body 115 by engaging them with each other.

As a result, the web using the first surface is brought to the position of the shaft 108 in FIG. 10 in a state where it is wound around the shaft 109, and the web portion contacting the web roller 110 'is fixed to the fixing roller 101. It comes into contact with and is rubbed against it by the spring 111 '. At this time, since the unused second surface 112 of the web contacts the fixing roller, sliding cleaning is performed in the same manner as in the initial case.

With this structure, the cleaning web can be effectively used on both front and back surfaces. It should be noted that the position reversal timing of the web unit can be accurately determined by providing an appropriate mark such as a red line on the edge of the web near the axes 108 and 109. Further, when the back side of the web is used, the amount of the release agent impregnated is small. Therefore, when the back side of the web is used, the web feed amount per transfer material is increased.
That is, it is possible to compensate for the shortage of the amount of the release agent by increasing the feeding speed.

However, in such a method, since the feed amount is remarkably different when the first surface and the second surface of the web are used, the speed change mechanism therefor becomes complicated, and in terms of cost, required space, etc. In addition, there is a problem in terms of the life of the web, and there is a problem of abrasion of the fixing roller due to the increased rubbing speed.

The present invention has been made to cope with such a situation as described above, and in a fixing device that utilizes both front and back surfaces of a cleaning web that contacts the fixing roller of the fixing device, the cleaning surface of each of the cleaning surfaces of the web is used. At the time of use, the amount of release agent applied is made uniform to stabilize its function,
An object of the present invention is to provide a fixing device capable of extending the life of the web.

[0017]

Configuration of the Invention

In order to achieve the above object, the present invention allows a transfer material to pass through a contact portion between a first traveling member and a second traveling member that abuts against the first traveling member. The fixing device includes a cleaning member that slides and runs on the first traveling member to perform cleaning, and when the first surface of the cleaning member is consumed,
In a fixing device of an image forming apparatus in which the cleaning member is reversed and cleaning is performed by the second surface of the cleaning member, the contact pressure or (and) contact width of the cleaning member with respect to the surface to be cleaned is set to the first surface and the second surface. And a fixing device that is different from the above, or a fixing device that is a roller used as the first and second traveling members in the above, or a surface to be cleaned by the second surface of the cleaning member in any of the above. The contact pressure or (and) width to the first
The fixing device described above is larger than that of the surface.

With this configuration, the amount of the release agent applied to the surface to be cleaned can be made uniform over the entire length of the front and back surfaces of the cleaning member, and the life of the cleaning member can be extended.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS "FIG. 1" is a side view of a fixing device showing an embodiment of the present invention, and its structure is basically the same as that of the known fixing device shown in "FIG. 9". A reference numeral corresponding to the number obtained by subtracting 100 from the reference numeral of each part of the known device is attached to each part, and description thereof will be omitted unless necessary.

In brief, the transferred transfer material S supplied to the pressure contact nip portion between the fixing roller 1 which is the first traveling member and the pressure roller 2 which is the second traveling member is transferred to the nip portion. It is assumed that the toner image is fixed and fixed on the transfer material by passing and is discharged to the outside of the apparatus.

A web unit 14 is removably arranged in the main body 15 of the apparatus including a fixing roller and the like, and the web unit 14 is also provided with shafts 8 and 9 for both take-up and rewind. A cleaning web 12, which is a cleaning member, is suspended. Furthermore, both axes of the web 8, 9
The portion between the two is engaged with the web rollers 10 and 10 ′, and when the web unit 14 is mounted as shown in the figure, the first surface of the web 12 contacts the fixing roller 1 via the web roller 10. When the web unit is turned upside down and mounted on the apparatus main body 15, the second surface of the web 12 comes into contact with the fixing roller via the web roller 10, and the fixing roller surface is rubbed and cleaned.

When the web unit 14 is mounted on the fixing device main body 15 as shown in the drawing, the web 12 is applied to the fixing roller 1 by the web roller 10 at the contact pressure P ₁ determined by the spring 11, as described above. Pressure contact. At this time, the web roller 10 'and the spring 11' are not in use.

FIG. 2 is a plan view of an essential part of the web unit. In the case shown in FIG. 1, the gear 18 mounted on the drive shaft 17 meshes with the gear 20 provided on the shaft 9. The shaft 9 is driven to wind the web.

When the web 12 wound around the shaft 8 is unwound in sequence and its first side is used up, the web 12 is shown in dotted lines in the figure below "Fig. 3" in the web unit 14. It is wound around the shaft 9 as shown. In this state, the dowel 13 and the cutout hole 7 on the web unit side.
a, and the web unit 14 is turned upside down as shown by the removal arrow in FIG.
4 by engaging the notch hole 7b and the dowel 13 with each other.
To the main body 15.

As a result, each part of the fixing device including the web unit 14 is positioned as shown in FIG.
The web roller 10 ′ is actuated by the spring 11 ′ so that the fixing roller 1
The contact pressure P ₂ is applied. Further, as shown in "Fig. 5", the gear 19 arranged on the shaft 8 side meshes with the gear 18 provided on the drive shaft 17, and the gear 12 of the web 12 is moved in the same manner as in the case shown in "Fig. 1". By the two surfaces, the rubbing cleaning of the fixing roller 1 can be executed.

When the cleaning is performed by the second surface of the web, the urging action of the spring 11 'is made larger than that of the spring 11 (when the cleaning constant is made higher than that of the cleaning by the first surface). , Increase the displacement of the spring), or replace the web roller 11 'with the web roller 11
The release agent leaching from the web and adhering to the fixing roller is different between the first surface cleaning and the second surface cleaning by means such as making the surface harder (the contact surface is made smaller and the contact pressure is made larger). It should be set so that it does not exist.

FIG. 6 is a graph showing the relationship between the pressing force per unit area and the web thickness when a load is applied to the web. According to this, P ₂ = αP ₁ (α> 1), and Δ ₁ <Δ ₂ when the web compression amounts at that time are Δ ₁ and Δ ₂ .

The thinner the web is, the smaller the space in which the release agent impregnated into the web can remain. Therefore, the compression amount must be increased to increase the discharge amount of the release agent.
Therefore, the second surface contact pressure P ₂ is α times the first surface contact pressure P ₁ (α
By setting> 1), the discharge amount of the release agent on both surfaces can be made uniform.

In this case, the value of P ₁ is 0.5-1.
The value of 5 [g / mm ² ] and α is preferably about 1.5 to 3.0.

FIG. 7 is a side view of a fixing device showing another embodiment. Portions corresponding to those in the apparatus shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In the illustrated apparatus, two web rollers 10a and 10b are provided as means for contacting the second surface of the cleaning web with the fixing roller 1. Therefore, in the case of the first side cleaning shown in the figure, there is no particular difference from the apparatus shown in FIG. 1, but the web unit 14 is turned upside down from the position shown in the figure so as to be cleaned by the second side of the web. When set to 15, both rollers 10a and 10b are in pressure contact with the fixing roller 1, and the intermediate web portion thereof is also in contact with the fixing roller 1 by the traction force acting on the web.

Therefore, in the case of the first surface cleaning,
The length of the web in contact with the fixing roller 1 in the circumferential direction is about several millimeters, whereas in the case of the second surface cleaning, the web can contact up to about several tens of millimeters, and the contact width can be arbitrarily determined. In this way, the second surface of the web 12 is brought into contact with the fixing roller with a wider surface, and the time for applying the impregnated release agent is extended to increase the amount of release agent applied on the second surface. Can be made.

FIG. 8 is a side view of a fixing device showing still another embodiment. In each part of this apparatus, the parts corresponding to those of the above-described respective embodiments are designated by the same reference numerals. In the illustrated apparatus, the sheet metal material 21 is disposed at a position corresponding to the web roller 10b of the apparatus shown in FIG. 7, and the web 12 is arranged together with the web rollers 10 and 10 '. It is suspended so that it also engages.

With this structure, when the web unit 14 is turned upside down and mounted on the main body 15, the web portion between the web roller 10 'and the sheet metal material 21 abuts the fixing roller 1 and the second surface At the time of cleaning, it is possible to extend the contact width and achieve the same operation as that of the apparatus of the above embodiment.

In the apparatus of the above embodiment, the contact pressure and the contact width are independently increased, but it is of course possible to combine these in one apparatus, and thus, By configuring the second of the web
It is possible to secure an increase in the release agent during the surface cleaning and further improve the stability of the cleaning function.

[0036]

As described above, according to the present invention,
A fixing device for fixing a toner image to a transfer material by passing through a contact nip portion of a pair of rollers that press the transfer material carrying an unfixed toner image against each other. In the fixing device, a web for cleaning the surface is disposed, and when the first surface of the web is consumed, the unused second surface of the web is brought into contact with the surface to be cleaned. When cleaning the two surfaces, the contact pressure and / or contact width (length in the running direction) with which the web contacts the surface to be cleaned is made different from that in the first surface cleaning, and the web is separated over the entire length of the front and back surfaces. It is possible to make the amount of the mold material applied to the surface to be cleaned uniform, to perform stable and good fixing at all times, and to extend the life of the cleaning member. That.

[Brief description of drawings]

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

FIG. 2 is a plan view of an essential part showing the drive system of the above.

FIG. 3 is a side view showing that the web unit is inverted as above.

FIG. 4 is a side view of the fixing device showing a state after reversing the same as above.

FIG. 5 is a plan view of an essential part showing a mode of a drive system after reversal.

FIG. 6 is a graph showing changes in pressing force and web contact.

FIG. 7 is a side view of a fixing device according to another embodiment.

FIG. 8 is a side view of a fixing device showing still another embodiment.

FIG. 9 is a side view showing a known fixing device.

[Explanation of symbols]

 1 Fixing Roller 2 Pressurizing Roller 3 Transfer Material Guide 4 Temperature Detection Thermistor 5 Separation Claws 8 and 9 Winding and Rewinding Shafts 10 and 10 'Web Rollers 11 and 11' Spring 12 Cleaning Web 14 Web Unit 15 Fixing Device Main Body 17 Drive shaft 18, 19, 20 gears

Claims (3)

[Claims] 1. A fixing device which allows a transfer material to pass through a contact portion between a first traveling member and a second traveling member that abuts against the first traveling member, the sliding member being rubbed against the first traveling member. In a fixing device of an image forming apparatus, which comprises a cleaning member for performing cleaning, and when the first surface of the cleaning member is consumed, the cleaning member is reversed and cleaning is performed by the second surface of the cleaning member. A fixing device in which the contact pressure and / or the contact width with respect to the cleaning surface is different between the first surface and the second surface. 2. The fixing device according to claim 1, wherein the first and second traveling members are rollers. 3. The contact pressure or (and) width of the second surface of the cleaning member with respect to the surface to be cleaned is made larger than that of the first surface according to claim 1 or 2. Any one of the fixing devices.