JPS60176075A - Fixing device - Google Patents

Abstract

PURPOSE:To keep a fixing function stable extending over a long period of time by not only supplying a cleaning agent used for general paper, but also making a cleaning web contact by pressing, and reinforcing the cleaning, when using a special kind of recording material such as a transparent film (OHP film). CONSTITUTION:When fixing a toner image T on a general paper 13, it is made to pass through between a fixing roller 23 and a pressure roller 24, and a cleaning agent in a bottle 25' is supplied by felt 25 through an upper pressure roller 22. When fixing a toner image T on a special kind of recording material 28 whose surface is smooth, such as an OHP film, said cleaning agent is supplied from the felt 25, also a roller 30 is made to contact by pressing to the fixing roller 23 by driving a motor M, and the cleaning is reinforced by supplying the cleaning agent from a cleaning web 26. In such a way, an offset phenomenon caused by a molten toner is obstructed effectively, the contamination of the surface of the fixing roller 23 is prevented, a stable fixation is executed extending over a long period of time, and a consumption of the cleaning agent is curtailed. This device is especially suitable for a color.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention relates to a fixing device applied to image forming apparatuses such as electrophotographic copiers, printers, and recording machines.

(2) Prior art and issues to be solved Heat fixing in which a recording material such as paper or resin film that carries a transferable toner image formed on the surface of an image carrier is heated to fuse and fix the toner image to the transfer material. Apparatus and pressure fusing devices are well known in the art.

FIG. 1 is a schematic side view showing the main parts of a known fixing device of this type that uses a heating roller. A pressure roller 1 and a lower pressure roller 3 are disposed under pressure and are heated to a predetermined temperature by a heater or other suitable heat source. An offset preventive agent such as silicone oil is applied to the upper pressure roller 1 in the oil reservoir 6a.
A suitable amount of oil is supplied by a supply material 6b made of felt or other suitable material, which sucks oil from this and supplies it to the surface of the roller 1, and this oil is further supplied and applied to the fixing roller 2.

From the right side of the figure, a recording material 4 carrying a toner image is supplied to the nip between the fixing roller 2 and the lower pressure roller 3 and heated, and the toner is melted and firmly adhered to the recording material and fixed. and then ejected from the aircraft. The silicone oil supplied to the fixing roller 2 has the effect of preventing the so-called offset phenomenon in which the toner that melts and increases in viscosity separates from the transfer material and adheres to the roller 2, which then adheres to the transfer material that is supplied next. It is something to do. Fixing devices with this type of configuration have been well known for a long time, but when paper is used as a recording material, molten toner gets stuck between the fibers of the paper. Therefore, there is little risk of toner adhering to the fixing roller side and causing an offset phenomenon, and even a very small amount of toner adhering to the fixing roller side circulates around the fixing roller surface, contacts the transfer paper again, and is removed.
Since it is subjected to a kind of cleaning action, the above-mentioned configuration can prevent the offset phenomenon to a practical extent.

However, when using a recording material made of hard resin with a smooth surface, such as a transparent film (OHP film) for an overhead graziector, the offset phenomenon is likely to occur, especially when fixing. When a silicone rubber roller is used as the roller, the durability of the roller is inevitably reduced.

Conventionally, offset toner adhering to the surface of the fixing roller is usually removed using a cleaning member such as a blade, felt, roller, or web. Generally, the cleaning member is always in contact with the surface of the fixing roller, or
As stated in each publication, the fixing roller is brought into contact with the surface of the fixing roller only when the recording material passes through it, but when fixing the toner image on the above-mentioned resinous transfer material, cleaning failures occur. .

On the other hand, in devices that use a web cleaning member, there have been proposals to increase the cleaning effect by variable control of the web feed amount and speed, but when fixing a toner image on the resinous transfer material mentioned above, cleaning problems may occur. In addition, the amount of web consumption increases, which is rather uneconomical.

The present invention differs from such conventional techniques in that the type of recording material (
Based on the technical concept of controlling the contact and separation of the cleaning member from the fixing roller surface according to the surface smoothness of the resin sheet), the durability of the fixing roller is significantly reduced even when various types of recording materials are used. The purpose of this is to expand the scope of use of the device without having to do so, thereby achieving cost savings.

(3) Purpose of the Invention The present invention has been made in view of the above-mentioned drawbacks of the known fixing devices, and provides a fixing device that uses a resinous recording material such as an OHP film. This method solves the problem of fixing by using a cleaning means that can immediately remove toner attached to the fixing roller or silicone oil contaminated by the toner dissolved therein.

(4) Description of structural functions and embodiments of the invention In the following embodiments of the invention, a fixing roller provided with a rubber surface layer is used in a fixing device using a pair of heating rollers for an image forming apparatus to which the present invention is particularly effective. A cleaning web is arranged so as to be able to move toward and away from the fixing roller, and the web can selectively come into contact with or separate from the fixing roller depending on the characteristics of the transfer material used, as shown in the attached drawings below. Embodiments of the present invention will now be described.

FIG. 2 shows a case where the fixing device according to the present invention is applied to a color copying machine, in which the copying machine body 2 is provided with a photosensitive drum 16 and a transfer drum 15 disposed close to it. A developing device group, a light image projection mechanism C equipped with a photolysis function, and other members are arranged around the photosensitive drum in order to form a transferable toner image thereon, but these are not included in the present invention. Since they are not directly related, explanations about them will be omitted.

The operation panel on the top surface of the copying machine is provided with a numeric keypad and other predetermined keys, as well as a switch 9 for plain paper and a switch 10, shown as a trap pen, for selecting a recording phase such as resin film. When the main switch 7 is turned on, the plain paper mode switch 9 is selected, and the copy switch 11 is turned on, the plain paper 13 ejected from the cassette 12 installed in the copying machine main body is
It passes through the conveyance path 14 and is wound and supported on the transfer drum 15.
After receiving the transferable toner image on the photosensitive drum 16 at the position of the transfer charger 18, it is separated from the transfer drum 15 by the separation claw 19 and reaches the fixing device 21 via the conveyance path 20.

As shown in FIG. 4, the fixing device 21 includes a fixing roller 23 with a silicone rubber layer on its surface, upper and lower pressure rollers 22 and 24 with a Teflon coating, a silicone oil reservoir, and a silicone oil reservoir. It is equipped with an oil supply mechanism 25 consisting of a supply member made of felt or the like that supplies an appropriate amount of internal oil to the surface of the upper pressure roller 22, and is also movable toward and away from the fixing roller 23, and a motor M. cleaning web 2 driven by
6 are arranged.

'As mentioned above, when the plain paper mode 9 is selected using the operation panel 8vc, the cleaning web is assumed to be in the retracted position as shown by the dotted line in FIG. Therefore, the fixing device operates in the same manner as the known one shown in FIG.
It is assumed that the transfer paper 13 supplied between the fixing roller 23 and the pressure roller 24 is fixed at this position and is discharged from the machine as it is.

When using a resin film or the like as a transfer material, when the switch 10 labeled ``TRAPEN'' is turned on on the operation panel 8, the film 28 is taken out from the cassette 27 containing the film and passed through the conveyance path 14. It is wound and held on the transfer drum 15, and after a monochromatic image or a color image is formed by one or several developing devices in the same way as in the above case, it is separated from the drum 15 by a separating claw 19 and sent through a conveyance path 20. Then, it reaches the fixing device 21.

When using a resin film like the one mentioned above, the molten toner does not enter the film during the fixing process, so it tends to adhere to the fixing roller side, and especially in the case of color images, OI-11) Projection using a film When printing, it is necessary to sufficiently heat and melt the toner in order to eliminate color stains, but this increases the adhesion force between the fixing roller and the fused toner, and the toner conversely moves into the structure of the silicone rubber roller. Furthermore, some of the toner dissolves into the silicone oil in the high fixing temperature tank, and this contaminated oil enters the structure of the silicone rubber roller, causing deterioration of the surface of the silicone rubber roller and preventing mold release. Therefore, it was inevitable that the durability of the fixing roller would be significantly impaired. Such inconveniences can be solved by the present invention.

When this film 28 is separated from the transfer drum 15 by the separating claw 9, the web 26 is brought to the position shown by the solid line in FIG.
3. The pressure roller 24 shall be in a low speed rotation mode so as to sufficiently heat the film.

In this case, although the mechanism for bringing the web 26 into contact with and away from the fixing roller is not particularly illustrated, for example,
A spring is engaged with the shaft of the roller 30 in the figure to bias it to one side, and by detecting the progress of the transfer material and energizing and deenergizing the solenoid, the roller 30 resists the action of the spring.
Therefore, any known appropriate means, such as bringing the web 26 into contact with and away from it, can be used.

Therefore, the film passing between these rollers is sufficiently melted and fixed there.

Along with this, melted toner that adheres to the fixing roller during the fixing process and silicone oil that is contaminated by the toner are removed.
It is assumed that the cleaning web is removed by a cleaning web that is moved by a motor M at an appropriate speed in the direction of the arrow in the figure.

The cleaning web is driven while the film passes between the pair of rollers 23 and 24, but the web 26 is kept sliding against the fixing roller 23 until a certain period of time has elapsed after the trailing edge of the film passes through the pair of rollers. After that, it is moved back to the dotted line position in Figure 4.

FIG. 5 is an example of a timing chart showing the temporal relationship between the pair of fixing rollers, the advance and retreat of the cleaning web, and the operation of the opening drive motor.

The reason why the nib is rubbed against the fixing roller for an hour after the film has passed is to ensure that the molten toner discharged from the trailing edge of the film adheres to the fixing roller, so this is removed. Therefore, it is preferable that the predetermined time be a time corresponding to at least one rotation of the fixing roller.

FIG. 6 is an explanatory diagram of another embodiment of the present invention.

As explained in FIG. 4, the fixing roller 23 has an elastic rubber layer 2 such as a silicone rubber layer or a mixed layer of rubber and resin.
3a is provided, and an upper pressure roller 2 is provided on this surface.
2 and the lower pressure roller 24 are in contact with each other. The upper pressure roller 22 is also a cleaning roller that heats the fixing roller 23 and applies anti-offset liquid, and at the same time cleans toner from the fixing roller 23. A felt 25a for supplying anti-offset liquid is in contact with the surface of the upper pressure roller 22, and a cleaning roller 31 is in contact with the upstream side of the felt 25a.

Reference numeral 40 denotes a speed changing means for controlling the rotational speed of the driving means 41 that drives each roller 31, 22, 23, 24, respectively.
A speed V' lower than that is applied to the drive means. A signal from the normal display 9 indicating the use of normal paper or a signal A from the special display 10 indicating the use of the special recording material 13 is inputted to the speed changing means 40, and the signal A from the special display 10 indicating the use of the special recording material 13 is inputted to the speed changing means 40, and the signal A from the special display 10 indicating the use of the special recording material 13 is inputted to the speed changing means 40. means 43 detection signal (outputs 1 only when special recording material is detected, outputs O when normal paper is detected) and input displays 9 and 10
It has a built-in malfunction prevention mechanism that compares the signals from the printer and provides a speed suitable for the recording material being used. Therefore, the driving means 41 is controlled so that the recording material being used is given a fixing speed suitable for its type.

37 is a web pressing roller 30. which is an example of auxiliary cleaning means. Web26. Web pressing roller 3
Plunger 38°, which performs contact and separation of The actuation of the separating means and the actuation controller 39 are controlled. The control means 37 outputs a signal only when the special type display 10 detects the use of a special recording material and the signal B detects that the separating claw 19 has come into contact with the transfer drum 15. When both the output signal from the AND circuit 34 and the signal A' from the recording material detecting means 43 indicating that the recording material used is a special recording material are inputted to the AND circuit 34 which outputs The plunger 38 and the actuation controller 39 are actuated by the input of the signal E from the AND circuit 35, and the plunger 38 is turned on only for the time t necessary for cleaning, and at the same time the suppression roller 30 is turned on. The elastic rubber layer 2 of the fixing roller 23 is
It has a timer 36 as a contact time control means for causing the contact point 3a to be pressed. When this time t has elapsed, the power to the plunger is turned off, and the pressing roller 30 is moved by an amount that separates the web 26 from the surface of the roller 23, and is held at the position indicated by the broken line in the figure.

In this example, when the transmitted light detector 32 is used as the recording material detecting means 43 and the amount of transmitted light is greater than a predetermined value (it is assumed that the amount of transmitted light is large when the special recording material is a resin sheet), Although a comparator 33 is used which outputs a signal A' indicating that the paper is a recording material, and does not output a signal when the paper is normal paper, other configurations may be used as long as the detection means is used to prevent malfunctions of this embodiment.

Now, in the drawing of FIG. 6, the operator specifies the use of the special recording material in advance, and the signal A is output from the special display 10. A is input, and in response, the driving means 41 drives the pressure rollers 22, 24 and 30-ra of the fixing roller 23 at a speed v' for the special recording material (lower than the normal paper speed V).

Thereafter, in the color copying machine shown in FIG. 2, the special recording material 13 on which the monochromatic or full-color toner image has been formed is moved onto the transfer drum 15 by the separating claw 19 that comes into contact with the transfer drum 15 to separate it. At the same time as the recording material is separated from the recording material, the type thereof is determined by the used recording material detection means 43.

The result detecting means 43 confirms that the selected special recording material is actually being used, sends the signal A' to the speed changing means 40 to check the speed V, and simultaneously sends it to the AND circuit 35. The AND circuit 34 inputs the signal B indicating the action of the separating claw 19 and provides a signal to the AND circuit 35, which receives the signal and outputs the signal E to operate the timer 36 for one hour.

As a result, the cleaning web 26, such as the cleaning plunger 38, can exert an auxiliary cleaning effect only on the special recording material, as shown in the drawing by the pressing roller 30.

Further, the used recording material detection means 43 sends a signal A to the speed changing means 40 if the designated recording material is normal paper and the actual used recording material that has been delayed is a special recording material made of resin. ′
The feed speed is changed to a speed V' which is slower than the speed ■, and at the same time, the signal A' is inputted to the OR circuit 44, and the AND circuit 3
4 to input signal A. Therefore, the web 26 as an auxiliary cleaning member is pressed against the fixing roller 23, and the cleaning effect can be maintained without malfunction.

Even if the recording material is erroneously fed in this manner, a malfunction prevention means is provided to ensure that the cleaning member operates only when a special recording material is used. This makes it possible to remove offset toner that occurs when a malfunction occurs, so if you have an oil applicator, there is no need to degrade the applicator function, and if you use a rubber material for the fixing roller, you can improve the durability of the roller. . Also, in the opposite case to the above case, i.e., when it is normal paper that actually causes the delay, web consumption is reduced when the cleaning member is a web or the like, or when the fixing roller is made of rubber material, the cleaning member If the fixing roller has a mechanism that can prevent wear caused by the fixing roller or change the fixing roller speed,
In particular, it is possible to prevent excessive fixing or non-fixing processing and reduce the amount of offset.

The above embodiment of the present invention is an example of a three-roller fixing device, but
The present invention is not limited to this, but is also effective in a two-roller fixing device, and it is particularly effective to provide a cleaning member used only for special recording materials on the roller that comes into contact with the toner. However, it may be provided on another fixing roller involved in fixing.

Furthermore, when the above-mentioned apparatus is provided with an anti-offset liquid applying means and/or a cleaning member, the present invention can produce unique effects in each case.

In the embodiment shown in FIG. 6, in addition to the roller 22 as a normal cleaning member, a web 26 as an auxiliary cleaning means is positioned before the offset toner reaches the cleaning roller 22, so cleaning defects on special recording materials can be more reliably prevented. can be prevented. In particular, in this example, the durability of the fixing roller surface layer 23a is improved by the above structure, and at the same time, the fixing roller surface layer 23a is brought into contact with the cleaning roller 22 and the roller 22
It is possible to improve the life of the roller 31 for cleaning the roller 31, to prevent the felt 25a as an oil applying member from becoming dirty, to stabilize uniform oil application, and at the same time to largely prevent the occurrence of offset.

In this way, in the present invention, the auxiliary cleaning means acts only on special recording materials such as resin recording materials among the recording materials. ) Problems in each case can be solved in each case, such as replacing the fixing roller, poor coating when equipped with anti-offset liquid application means, and replacing this roller when equipped with a permanently installed cleaning roller, etc. The durability of even 100 sheets of special recording material has been improved. In particular, the present invention has the great effect of realizing the use of special recording materials in color copying machines.

Furthermore, FIG. 6 shows that the fixing speed for special recording material is made slower than that for regular paper to improve the cleaning effect and fixing effect, and the friction between the additionally acting auxiliary cleaning means and the fixing roller surface layer 23a. The effect of reducing wear due to friction and charging, and enabling long-term use of the fixing roller is important. This effect is particularly effective for elastic fixing rollers, but it is not limited to elasticity as it can also be obtained with other resin layers.

In addition, this embodiment has a malfunction prevention means that can check the recording material actually used, so it prevents the use of unnecessary auxiliary cleaning means, achieves cost savings, and also prevents the fixing roller from being used. It is possible to reliably prevent shortening of life due to malfunction. In this sense, the fixing roller does not need to have an elastic surface layer.

The auxiliary cleaning means in this embodiment includes a cleaning blade, a roller, and a web.

Although various materials such as felt can be used, a roller or a web that rotates for cleaning is preferable, and a web cleaning that does not damage the elastic surface is particularly good.

Further, as the control means 37, the used recording material detection means 43, and the means (plunger 38 and pressing roller 30) for moving the auxiliary cleaning member toward and away from each other, any means other than the above-mentioned embodiments can be used as long as it can achieve the above-mentioned purpose.

(5) Effect The present invention has the above-described structure, and fixing is difficult only when using a special recording material such as OHP film, which is hard and has a high degree of surface smoothness, such as resin. Since the cleaning member is rubbed against the fixing roller in the device to remove toner and other deposits on the surface of the roller, it effectively prevents the offset phenomenon caused by molten toner and prevents the fixing roller from being contaminated with silicone oil. By preventing deterioration of the rubber layer on the surface, stable fixing function can be maintained over a long period of time, and the consumption of cleaning materials can be saved, so the mechanism can be downsized and costs can be reduced. .

Although the above embodiment describes the most suitable case in which the present invention is applied to a color copying machine, it is easy to understand that similar effects can be obtained in image forming apparatuses using other electrostatic processes. I guess it's possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing the configuration of a known heat fixing device, FIG. 2 is a side sectional view of a copying machine to which the fixing device according to the present invention is applied, FIG. 3 is a plan view of the operation panel, and FIG. , a side view of essential parts showing an embodiment of the fixing device according to the present invention, and FIG. 5 is a timing chart showing the relative operation of the fixing roller, the cleaning web, and the driving motor. FIG. 6 is an operational explanatory diagram showing another embodiment of the present invention. 1.22... Upper pressure roller, 2, 23... Fixing roller, 3, 24... Lower pressure roller, 26... Cleaning web, 37... Control means, 43... Recording material detection means. Figure 1

Claims (3)

[Claims] (1) In a fixing device that drives at least one pair of rollers and fixes a toner image on the recording material by passing a recording material between the pair of rollers, contacting one roller of the pair of rollers is provided. A fixing device comprising: a cleaning member for cleaning the resin recording material; and means for bringing the cleaning member into contact with the roller only during fixing to fix the resin recording material to the resin recording material. (2) Claims in which the contact means includes means for detecting the type of recording material used, and means for preventing malfunction of the contact/separation state of the cleaning means according to the detection result of the detection means. The fixing device according to item 1. (3) The driving means includes speed changing means for making the rotational speed of the roller faster than the normal rotational speed of the recording material when the cleaning member is brought into contact with the roller by the contacting means. 1st term or 2nd term
Fixing device as described in section.