JPH03282579A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a toner offset over a long period by providing a conductive cleaning member being in contact with a fixing roller to clean its surface and applying a bias to the cleaning member. CONSTITUTION:In the cleaning device 17 of the fixing roller 1, an nickel-plated web 190 is used; a web as a cleaning member has electrical conductivity, and is plated with nickel which is a material having high surface energy. The web 190 is rolled up and mounted on a feeding shaft made of metal, and the feeding shaft 18 and the nickeled layer of the web 190 are electrically conducted, and engaged with a taking up shaft 21 via a pressing roller 20 pressing the web 190 on the face of the roller 1. The rotating/driven roller 1 is electrified to a negative polarity the same as that of the bias by the press-contact of the web 190 where a negative bias is applied from a bias applying power source B. Thus, force for electrically repulsing toner having negative electrifying properties acts on the roller 1, and the toner offset is effectively suppressed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to image forming apparatuses (or image forming methods) such as copying machines, laser beam printers, microfilm reader printers, facsimile machines, image display devices, and recording machines. , directly or indirectly (transfer) onto the surface of an image bearing member (electrofax sheet, transfer material sheet, electrostatic recording sheet, printing paper, etc.) using an appropriate image forming process means such as electrophotography, electrostatic recording, or magnetic recording. The present invention relates to a fixing device that fixes an unfixed toner image corresponding to target image information formed by the ) method as a fixed image on the surface of an image bearing member carrying the toner image.

More specifically, fixing methods include a rotating body (such as a roller body or a rotating endless belt body) that fixes an image by contacting a member carrying an unfixed image, such as a heat roller method or a pressure port-ra method. Regarding equipment.

(Prior Art) Conventionally, this type of fixing device has a member that carries an unfixed toner image between a pair of rotating rollers in pressure contact with a fixing (heating) roller whose temperature is maintained at a predetermined temperature and an opposing (pressure) roller. A heat roller method is often used in which a toner image is fixed on the surface of the recording material by heat and pressure by introducing and passing a recording material (hereinafter referred to as a recording material).

FIG. 10 shows a schematic configuration of an example of a heat roller type fixing device.

Reference numerals 1 and 6 designate a pair of vertically parallel fixing rollers and pressure rollers that are brought into contact with each other with a predetermined contact pressure. Fixing roller 1
The pressure roller 6 is rotationally driven in the direction of the arrow at a predetermined speed by a drive device (not shown).

The fixing roller 1 is attached to the outer periphery of a hollow core metal 2 made of aluminum.
A TV silicone rubber layer (high temperature vulcanization type silicone rubber layer) 3 is coated to a predetermined thickness, and an RTV silicone rubber layer (room temperature vulcanization type silicone rubber layer) 4 is further coated on the outer periphery.
is coated with a thickness of 200 μm, and the hollow core metal 2
A halogen heater 5, which is a heating source, is inserted into the inner space.

The pressure roller 6 is attached to the outer periphery of the aluminum hollow core metal 7.
A TV silicone rubber layer 8 is coated to a predetermined thickness, and a fluororesin coating 9 is further formed as a surface layer on the outer periphery, and a halogen heater 10 as a heating source is installed inside the hollow core bar 7. It is an insertion arrangement.

A thermistor 11 is brought into contact with the outer surface of the pressure roller 6, and a temperature control circuit (not shown) including this thermistor 11 controls the halogen heaters 5 and 5 of the fixing roller 1 and the pressure roller 6.
The temperature of the fixing roller 1 and the pressure roller 6 is set to a predetermined temperature appropriate for fixing the unfixed toner image Ta on the recording material P to the surface of the recording material P by appropriately controlling the supply of current to the recording material P on and off. (for example, 170°C).

Reference numeral 12 denotes a release agent coating device provided at a predetermined location of the fixing device in order to improve the releasability of the toner from the fixing roller 1. The mold release agent applicator 12 of this example applies silicone oil 14 as a mold release agent in an oil tank 13 to a roller group 15.
16, it is configured to apply and supply an appropriate amount onto one surface of the fixing roller.

Reference numeral 17 denotes a cleaning device provided at a predetermined location of the fixing device for wiping off toner offset on one surface of the fixing roller.

The cleaning device 17 of this example is of a web type,
A cleaning web 19 (trade name Nomex,
A fibrous web 19 is passed through a pressing roller 20 that presses the web 19 against the surface of the fixing roller 1, and is locked onto a winding shaft 21 and wound up little by little.
This is for cleaning the surface.

A recording material P, on which an unfixed toner image Ta has been formed in an image forming mechanism (not shown), is introduced between the fixing roller 1 and the pressure roller 6, which are being rotationally driven, from the roller guide 22, with the toner image bearing surface facing upward. As a result, the unfixed toner image is fixed Tb on the surface of the recording material P by receiving heat and pressure in the process of passing through the nip portion between the two rollers.

The recording material that has passed between the two rollers is discharged from the paper ejection guide 23.
The paper passes through a pair of paper discharge rollers 24 and is sent to a paper discharge tray or the like outside the machine.

(Problems to be Solved by the Invention) When the fixing process is performed, a portion of the toner is transferred and adhered to the surface of the fixing roller that contacts the toner image bearing surface of the recording material P (toner offset). In order to reduce and remove the amount of offset toner, the release agent coating device 12 and the cleaning device 17 as described above are provided. 17, the offset toner can be removed to properly clean the fixing roller 1. However, as the amount of offset toner increases, the cleaning device 17 cannot remove the offset toner completely, and the cleaning device 17 There is a phenomenon in which the offset toner that has slipped through the toner enters the nip between the fixing roller 1 and the pressure roller 6, which is the fixing section, and is transferred again to the surface of the subsequently introduced recording material, degrading the image quality.

In addition, the offset toner on the side of the fixing roller 1 transfers and adheres to the surface of the pressure roller 6 that is in direct contact with the fixing roller 1 when the paper is not passing through, staining the pressure roller 6 and causing stains on the back side of the recording material. It will also happen.

In particular, when it comes to fixing devices that fix a large amount of unfixed toner images in multiple layers of two or more colors formed on a recording material, such as a fixing device in a color or multicolor image forming device, offset toner is used. The amount of offset toner has also increased, and the life of the fixing device has shortened until it can no longer clean the offset toner.

The above applies not only to heat roller type fixing devices, but also to other types of fixing devices.
This is also a problem common to fixing devices such as pressure roller type fixing devices that include a rotating body that fixes an image by contacting a member carrying an unfixed toner image.

The present invention has been proposed in view of the above, and is an object of the present invention to suppress, over a long period of time, the original amount of toner offset with respect to the fixing rotor in this type of fixing device to a trace amount that can always be sufficiently removed by a cleaning device. ,
Furthermore, by increasing the offset toner collection ability of the cleaning means, there is provided a fixing device that prevents the offset toner from slipping through the cleaning device due to an increase in the amount of offset toner, and the above-mentioned adverse effects caused by the toner. The purpose is to

(Means for Solving the Problems) The present invention provides a fixing device including a rotating body that fixes an image in contact with a member carrying an unfixed toner image, and which cleans the surface of the rotating body in contact with the rotating body. A fixing device is characterized in that it has a conductive cleaning member and a means for applying a bias to the conductive cleaning member.

The present invention also provides a fixing device having the above-mentioned configuration, in which a bias having the same polarity as that of the toner is applied to the conductive cleaning member of the rotary body that is in contact with the image bearing surface of the member carrying the unfixed toner image, and the unfixed toner image is removed. A bias having a polarity opposite to that of the toner is applied to the conductive cleaning member of the rotating body that is in contact with the surface opposite to the image bearing surface of the carrying member, and a bias having a polarity opposite to that of the toner is applied to the conductive cleaning member of the rotating body. The fixing device is characterized in that the conductive cleaning member is made of a web plated with metal.

(Function) (1) One of the main causes of toner offset with respect to the rotating body is that the surface of the rotating body becomes charged due to contact between the pair of rotating bodies for fixing or with an image bearing member, etc. be.

If the charging polarity is opposite to that of the toner, the toner is electrically attracted to the surface of the rotating body and tends to cause offset.

For example, in the case of the above-mentioned fixing device, the fixing roller 1 whose surface material is silicone rubber is positively charged, and the pressure roller 6 whose surface material is made of fluororesin is negatively charged. If the toner carried on the recording material P introduced into the fixing device is negatively charged, a portion of the toner tends to be offset to the fixing roller 1.

Therefore, the cleaning member in contact with the rotating body is made conductive and a bias is applied to it, and the conductive cleaning member of the rotating body in contact with the image bearing surface of the member carrying the unfixed toner image is the same as the toner being carried. By applying a polar bias, a positive force that electrically repels the toner acts on the rotating body, effectively suppressing toner offset against the rotating body surface, and also preventing toner offset from occurring on the rotating body surface. Even if offset occurs, it is possible to suppress the amount of offset over a long period of time to a small amount that can always be sufficiently removed by the cleaning device for the rotating body.

Therefore, offset toner slips through the cleaning device due to an increase in the amount of offset toner on the rotating body surface,
This removal can prevent the harmful effects of toner over a long period of time.

(2) The cleaning member of the rotating body that is in contact with the surface opposite to the image bearing surface of the member carrying the unfixed toner image is made conductive, and by applying a bias of opposite polarity to that of the toner, the cleaning member is When fixing is performed, a force that electrically attracts the toner toward the surface of the image bearing member acts on the body.

This suppresses toner offset with respect to the rotating body that is in contact with the image bearing surface of the image carrying member, and toner offset with respect to the rotating body is more effectively prevented.

(3) It is also effective to apply a bias of opposite polarity to the toner to the conductive cleaning member of the rotating body. In this case, the offset toner of the rotating body is removed by the cleaning member that is in contact with the rotating body. The offset toner is efficiently removed from the surface of the rotating body by its own offset toner removal action and the positive electrical adsorption action of the offset toner to the cleaning member due to the bias of opposite polarity to the toner applied to the cleaning member, and the toner passes through the cleaning device. This prevents the offset toner from going around again to the fixing section, and the negative effects of the offset toner can be prevented for a long period of time.

(4) It is also a good idea to apply a bias directly to the core of the rotating body, but in this case, the structure that electrically floats the rotating body becomes complicated, or the bias is applied to the part where the rotating body is rotating at high speed. There are problems such as the method of inserting the metal is difficult, and the use of sliding electrical contacts to apply bias to the rotating core metal generates electrical noise.

In the present invention, the cleaning member in contact with the rotating body is used to make it conductive, and a bias is applied to the conductive cleaning member to directly apply the bias to the surface of the rotating body, so the above-mentioned problems are avoided. Furthermore, this type of direct bias application to the surface of the rotating body is highly effective in charging the surface of the rotating body, and a sufficient effect can be obtained with a much smaller applied voltage than when applying a bias to the core of the rotating body.

By using the web cleaning device for the rotating body as a web cleaning means using a conductive cleaning web, the web surface that comes into contact with the rotating body can be kept substantially clean at all times by winding the web. It becomes possible to always perform bias application efficiently and satisfactorily.

(Example) <Example 1> (Figures 1 and 2) Figure 1 shows a heat roller type fixing device according to the present invention, and the same components and parts as those in the example in Figure 10 described above are common. The reference numerals are given to omit further explanation.

In this embodiment, the cleaning device 1 for the fixing roller 1
7 is a cleaning member having a web 190 that is conductive.

Specifically, a nickel-plated web is created by plating nickel, a substance with higher surface energy than Nomex, using an electroless plating method on at least the roller contact side of a conventional heat-resistant nonwoven Nomex (trade name) web. The surface of the fibers of the web is coated with nickel to a thickness of about 0.1 μm and 3 g per web.

The nickel-plated web 190, which is the conductive cleaning member, is wound into a roll and attached to a metal unwinding shaft 18, and the metal unwinding shaft 18 and the web 19
The 0 nickel plating layer is electrically conductive. Further, this nickel-plated web 190 is electrically suspended from the main body of the fixing device.

The web 190 is then locked onto the take-up shaft 21 via a pressing roller 20 that presses the web 190 against one surface of the fixing roller. The surface of the nickel plating layer of the web 190 comes into pressure contact with the surface of the fixing roller.

B is a power supply for applying a bias to the nickel-plated web 190, and a bias having the same polarity as the toner (developer) carried on the recording material P introduced into the fixing device A is applied. In this embodiment, a toner having negative charging characteristics is used, and a negative bias is applied to the secondary nickel plated web 190.

The circumferential surface of the rotationally driven fixing roller 1 is charged to the same negative polarity as the bias polarity by contact with a nickel plated web 190, which is a conductive cleaning member to which a negative bias is applied.

Therefore, since a positive force acts on the fixing roller 1 to electrically repel the toner having negative charging characteristics, the recording material P that has entered the fixing section (the nip between the fixing roller 1 and the pressure roller 6) The offset of the carried toner with respect to one surface of the fixing roller, which is a negative charging characteristic of the cleaning device 1, is effectively suppressed.
7, it can be suppressed over a long period of time to a trace amount that can be sufficiently removed.

Even if the releasability of the surface of the fixing roller 1 deteriorates due to use and the toner starts to offset little by little, the cleaning function of the nickel-plated web 190 works to clean the surface of the fixing roller 1.

, the nickel-plated web 190 is moved around the winding shaft 21 at a predetermined speed (for example,
5 mm per 100 sheets of recording material. The nickel-plated web 190 is then rubbed against the surface of the fixing roller 1 as the fixing roller 1 rotates, thereby cleaning the surface of the fixing roller. In this case, since the nickel plated web 190 is fibrous, it is in good contact with the fixing roller 1, unlike a smooth and hard cleaning member such as a metal roller.

That is, the toner offset in some places on the surface of the fixing roller 1 is mixed with the fibers 190 of the web 190 as shown in the schematic diagram of FIG.
Since the toner is attracted between the fixing roller 1 and the nickel-plated web 190, the toner does not accumulate locally and the contact between the fixing roller 1 and the nickel-plated web 190 is good. And web 1
Since the toner 90 is fibrous, it is highly effective in wiping off the toner from the roller 1.

Further, the nickel contained in the side of the nickel-plated web 190 that contacts the fixing roller 1 adsorbs the toner on the fixing roller 1 well because metals such as nickel have high surface energy and high affinity with toner. As a result, the cleaning ability of the cleaning device 17 to remove toner from the fixing roller 1 is significantly improved compared to the conventional web. Therefore, as the fixing roller 1 is used, the releasability of the surface of the fixing roller 1 deteriorates, so that the toner strongly adheres to the surface of the fixing roller 1, or such toner can be easily removed.

Therefore, the winding speed of the nickel-plated web 190 in the present fixing device is conventionally 75 mm per 100 sheets of web in the case of a web made only of Nomex fibers, and the surface of the fixing roller 1 is always cleaned with a fresh surface of the web. While I was winding it as fast as I could, it was 1/15th of that time.
And it's late. Even in this case, as mentioned above, since the cleaning ability of the toner is high, the nickel plated web 1
90 can extend the life of the fixing roller until it is offset.

In fact, in the conventional device, offset occurs after 20,000 sheets, but in this embodiment, it is possible to extend the life of the roller due to offset up to 100,000 sheets.

Now, how to make the nickel plated web 190 will be explained.

Conventional non-woven fabric fibers made of Nomex are degreased with a solvent and then chemically etched.

This degreasing and chemical etching are performed using conventionally known methods.
Clean and roughen the fiber surface.

Furthermore, platinum is applied as a reducing agent, and then the fibers are passed through a nickel plating bath at a constant speed to electrolessly plate nickel metal onto the fibers. The amount of nickel deposited on the fiber is
During the above process, all the conditions are applied, but in particular, it greatly depends on the bath concentration of the electroless nickel plating bath and the speed at which the Nomex fiber passes through the plating bath.

Naturally, the higher the bath concentration, the greater the amount of nickel metal deposited per Nomex fiber, and the faster the speed at which the fibers pass through the bath, the smaller the amount of nickel metal deposited.

The Nomex fibers electrolessly plated with nickel are then washed with water and dried to form a conductive cleaning web.

In this example, 3 g of nickel is deposited per lrn' by appropriately adjusting the bath concentration and the speed at which the m fibers pass through the bath.

Furthermore, as described in (4) of (Operations) above, since the bias is applied directly to the surface of the fixing roller with the nickel-plated web 190, which is a conductive cleaning member that is in contact with it, the configuration of the bias application means is It is simple and has a high effect of charging the fixing roller surface, and the fixing roller 1
When applying a bias to the core bar 2 of the web 190, it is necessary to apply a voltage of -1 to -2 KV, whereas the voltage applied to the web 190 can be as low as -700 V to obtain a sufficient effect. Ta.

In addition, even if the web 190 becomes dirty with toner or the like, it is wound up little by little, and the part of the web surface that contacts the fixing roller 1 and applies a bias can always maintain a clean web surface, so it is always efficient against the fixing roller 1. Therefore, it became possible to apply bias effectively.

Embodiment 2 (FIGS. 3 and 4) In this embodiment, the cleaning member for the fixing roller 1 is a rotating roller body 190A (cleaning roller).

This cleaning roller 190A has a structure in which a nickel-plated web 193 similar to that used in Example 1 is adhesively wound around the outer periphery of a cylindrical roller 192 made of aluminum with the nickel-plated surface facing outward.

This cleaning roller 190A is the fixing roller 1.
It is brought into contact with a surface with a predetermined pressing force and rotated in the direction of the arrow by a drive device (not shown). Further, a bias applying power source B applies a negative voltage having the same polarity as the polarity of the toner carried on the recording material P introduced into the fixing device A (negative charging characteristics in this example).

The rest of the fixing device configuration is the same as in Embodiment 1.

The circumferential surface of the fixing roller 1 has a nickel-plated web 19 on the outer circumferential surface of a bias-applied cleaning port 190A that rotates in contact with the roller as the roller rotates.
3 m fibers are rubbed and negatively charged to repel toner, effectively suppressing toner offset, and
One surface of the fixing roller is cleaned.

The cleaning roller 190A rotates at a predetermined peripheral speed (for example, 1 mm per 100 sheets of recording material). In this way, the device of this embodiment also provides the same effects as the device of the above-described <Embodiment 1>.

<Example 3> (Fig. 5) In this example, in the fixing device A of <Example 1> described above,
A web-type cleaning device 17A using a nickel-plated web 190 as a conductive cleaning member similar to that applied to the fixing roller 1 is also provided for the pressure roller 6.

However, the web 190 of this cleaning device 17A has a charging characteristic (in this example, a negative charging characteristic) of the toner carried on the recording material P introduced between the fixing roller 1 and the pressure roller 6 by the bias application power source B/. A positive bias of opposite polarity is applied.

With this configuration, the surface of the pressure roller 6 is charged with a polarity that attracts toner to the surface of the recording material P, suppressing toner offset with respect to the fixing roller 1, and furthermore, the fixing roller 6 described in <Embodiment 1> When combined with the toner repulsion of the fixing roller 1 due to the bias applied from the roller side, toner offset with respect to the fixing roller 1 is more effectively prevented.

Further, the offset toner transferred to the surface of the pressure roller 6 is effectively transferred to the pressure roller 6 by the wiping action of the web 190 of the cleaning device 17A and the toner adsorption action by a positive bias having the opposite polarity to the toner applied to the web 190. Cleaned away from the surface.

In Examples 1 to 3, if the charging property of the toner carried on the recording material P is positively charging, the web 190 or the cleaning roller 19 serving as the cleaning member of the fixing roller 1
A bias applied to 0A becomes a positive bias.

The bias applied to the web 190, which is the cleaning member, of the pressure roller 6 in the straddling embodiment 3 is a negative bias.

As in Examples 1 to 3, the fixing roller 1 has at least its surface layer 4 made of a silicone rubber material, and the pressure roller 6
When at least the surface layer 9 of the cleaning member 190 is made of a fluororesin-based material, the cleaning member 190 is
The effects of the present invention are particularly noticeable by applying a negative bias to 190A.

<Example 4> In this example, in the fixing device of <Example 1> (Figs. 1 and 2), the bias application to the nickel-plated web 190, which is the cleaning member of the fixing roller 1, was determined based on the negative charge polarity of the toner. It has the opposite polarity, that is, a positive bias. The other device configurations are the same as those of <Example 1>.

In this case, the offset toner on the fixing roller 1 is generated by the cleaning action of the nickel-plated web 190, which is a cleaning member in contact with the fixing roller 1, and by the bias applied to the web 190, which has the opposite polarity to the toner. 190, it is efficiently removed from one surface of the fixing roller and prevented from slipping through the cleaning device 17 and returning to the fixing section, preventing the negative effects of offset toner from slipping off for a long time. did it.

That is, it is difficult for the offset toner of the fixing roller 1 to get around to the fixing section and cause stains on the subsequent surface of the recording material.In the conventional device, the toner slips through the cleaning device 17 after 20,000 sheets and offset occurs. In contrast, it has become possible to extend the life of the roller by offset up to 100,000 sheets.

In this embodiment, the offset toner on the fixing roller 1 is removed by a nickel-plated web 190, which is a cleaning member.
Is it possible to effectively clean the web 190 by electrostatically adhering it directly to the web 190 with a bias applied to the web 190?
Since the web 190 is charged at about 2 KV, the bias applied to the web 190 is preferably about +2.2 to +5 KV.

However, such a bias value is effectively set depending on the amount of charge on the fixing roller 1 depending on the configuration of the fixing device and the like.

<Example 5> This example uses the cleaning roller 19 which is a cleaning member of the fixing roller 1 in the fixing device of <Example 2> described above.
The bias applied to 0 A is the opposite polarity of the negative charge polarity of the toner, that is, a positive bias.

The other device configurations are the same as those of <Embodiment 2>.

The device of this embodiment provides the same effects as the device of Embodiment 4>.

<Example 6> This example uses the nickel-plated web 1 which is the cleaning member of the fixing roller 1 in the above-mentioned <Example 3> (FIG. 5).
The bias applied to the toner 90 is a polarity opposite to the negative polarity of the toner, that is, a positive bias. Web 190 serving as a cleaning member for pressure roller 6
The bias applied to the voltage remains positive. Other configurations are similar to <Embodiment 3>.

The device of this embodiment also provides the same effects as the devices of <Embodiment 3> and <Embodiment 4>.

<Example 7> (FIG. 6) In this example, as in the apparatuses of <Examples 4 to 6>, a bias having a polarity opposite to that of the toner is applied to the cleaning member 190 (190A) for the fixing roller 1. In this embodiment, a fixing roller surface static eliminator 25 is disposed downstream of the fixing roller contact portion of the cleaning member 190 (190A) in the fixing roller rotation direction and up to the pressure roller 6 pressure contact position. The static eliminator 25 in this example is a static eliminator brush.

That is, the cleaning member 190 of the fixing roller 1 (190
By applying a bias with a polarity opposite to that of the toner to A), the above-mentioned effects can be obtained; however, the surface of the fixing roller that has come into contact with the cleaning member is slightly charged with a polarity opposite to that of the toner. At the nip between the fixing roller 1 and the pressure roller 6), toner is likely to electrostatically adhere to the surface of the fixing roller 1.

Therefore, by disposing the charge eliminating brush 25 as described above, the charge on the surface of the fixing roller is eliminated and the electrostatic adhesion of the toner to the fixing roller 1 is weakened.

The static eliminator 25 is not limited to a static eliminator brush, but may also be a corona discharger that generates corona of the same polarity as the toner to re-charge the surface of the fixing roller, a member that neutralizes the surface of the roller by applying an AC bias, or the like.

<Example 8> (FIG. 7) This example differs from Examples 4 to 7 in that the cleaning member 1 is installed downstream of the fixing section in the rotational direction of the fixing roller 1.
A fixing roller surface static eliminator 26 is disposed at a position 90. (190A). The static eliminator in this example is a static eliminator brush.

That is, even if the surface of the fixing roller that has passed through the fixing section is strongly charged, by the time it reaches the cleaning member 190 (190A), the charge has been removed from the roller surface by the static eliminating brush 26, so that the cleaning member 190 (190A)
A good effect can be obtained by applying a small amount of bias to 0A).

Specifically, since the surface of the fixing roller is neutralized to almost 0, the bias against the cleaning member 190 is +7.
Approximately 00v is sufficient.

The static eliminator 26 is not limited to a static eliminator brush, but may remove the strong charge on the surface of the fixing roller by applying an AC bias using a corona charger or the like, or by applying a slight negative corona discharge.

This static eliminator arrangement can also be applied to the pressure roller 6.

In Examples 4 to B, when the charging characteristic of the toner carried on the recording material P is positively charging, the web 190 serving as the cleaning member of the fixing roller 1 or the cleaning roller 1
The bias applied to 90A is a negative bias. Further, the bias applied to the cleaning member 190 by the pressure roller 6 is a negative bias.

As a fixing device in a case where a large amount of offset toner tends to adhere to the fixing roller in order to fix a large amount of unfixed toner images of multiple layers, such as a fixing device in a color or multicolor image forming apparatus, Examples 4 to 8 The above fixing device is particularly effective.

In each of Examples 1 to 8 described above, a case was described in which a nickel-plated web in which a web made of Nomex was plated with nickel was used as the conductive cleaning member, but the present invention is not limited to this. A web made of aluminum plated with copper may also be used. When a durability test was conducted by applying a bias to a fixing device equipped with a cleaning device using such a cleaning member for a copper-plated web, the same effect as in the case of a nickel-plated web was obtained.

In addition, it is a matter of fact that the method of manufacturing a conductive web by plating Nomex with nickel is not limited to the electroless plating method described above, but that other methods may also be used. A metal coating may be applied to the web using a molding method or the like.

In addition, metals contained in xi include aluminum, Of course, copper or the like can also be used.

<Example 9> (Figures 8 and 9) This example is based on the fixing device A of <Example 1> to <Example 8>.
This is an example of an image forming apparatus using.

The image forming apparatus 50 of this example is a laser scanning exposure type/transfer type full color electrophotographic apparatus.

In FIG. 8, reference numeral 51 denotes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as photosensitive drum) as an image carrier, which is rotated at a predetermined circumferential speed (process speed) in the direction of the arrow.

During the rotation process of the photosensitive tram 51, an electrostatic latent image corresponding to the target image information is formed as a result of being charged by a charger 52 and subjected to laser beam scanning exposure by a laser scanner 53. is developed as a toner image by the developing device 54.

The developed toner image is fed to the transfer drum 55 and transferred onto the surface of a recording material (transfer paper) P held in a wound state.

The developing device 54 is a rotary rotary switching type color-specific toner developing device, and includes a magenta developer 54M and a cyan developer S.
4C/Yellow developer 54Y/Bragg developer 54BK
It has four color developing units, and the above four colors can be selected by switching signals.
The two developing devices are sequentially switched and moved to positions where they act on the photosensitive drum 50.

70M, 70C, 70Y, and 708 are toner hoppers for replenishing magent toner, cyan toner, yellow toner, and black toner, respectively, to the respective color developing units 54M, 54C, 54Y, and 54BK.

In this embodiment, the toners of each color have negative charging characteristics.

Reference numerals 56 and 57 denote a charger and a cleaning device for removing static electricity from the surface of the photosensitive drum 51 after passing through the transfer section.

58 and 59 are detachable first and second recording material cassettes.

The paper feed roller 60 or 61 corresponding to the first or second recording material cassette selected and designated in advance is driven to rotate in response to a paper feeding start signal, and the first or second recording material cassette 58 is rotated. Alternatively, one recording material P is fed from 59 to a sheet path 63 including a guide plate, conveyance roller, registration roller, etc.
The image is fed to the transfer drum 55 through the transfer drum 55 .

The transfer drum 55 is rotated in the direction of the arrow at the same predetermined circumferential speed as the photoconductor tram 51, and the leading edge of the recording material P fed to the transfer drum 55 hits the recording material gripper 55a of the transfer drum 55. By being held, the recording material P is conveyed to the transfer section in a state wrapped around the outer peripheral surface of the transfer drum 55, and in the transfer section, the photosensitive drum is charged by the transfer charger 64 disposed inside the transfer tram 55. The toner image formed and carried on the 51 side is transferred onto the surface of the recording material P on the transfer tram 55 side.

To explain the full color mode, the target image information is inputted from a host device (not shown) such as a full color image color separation decoding device or an electronic computer, and is modulated in response to a time-series electrical digital pixel signal of a magenta component image, and then sent to a laser beam scanner. An image forming process including scanning exposure of the photosensitive drum 51 by the laser beam outputted from the transfer drum 53 and development by the magenta developing device 54M is executed.
The magenta toner image is transferred onto the recording material P wrapped around and held by the recording material P. Hereinafter, an image forming process including laser beam scanning exposure corresponding to a cyan component image and development by the cyan developing device 54C, transfer of the formed cyan toner image, laser beam scanning exposure corresponding to a yellow component image and development by the yellow developing device 54Y will be described. The image forming process including the development by and the transfer of the formed yellow toner image, the image forming process including the laser beam scanning exposure corresponding to the black component image and the development by the black developer 548K, and the transfer of the formed black toner image are sequentially executed. Then, four toner images, magenta toner image, cyan toner image, yellow toner image, and black toner image, are sequentially superimposed and transferred onto the surface of the same recording material P wound around and held by the rotary transfer tram 55, and unfixed. A composite full-color toner image is formed.

When transferring the final black toner image, the clipper 55a holding the recording material P on the transfer drum 55 is released, and the recording material P is separated by the charger 65 for separating the recording material and the separating claw 66 inside the transfer drum. It is separated from the transfer drum 55 surface,
The unfixed toner is introduced between the fixing roller 1 and the pressure roller 6 of the fixing device A through the conveyance belt device 67 and the entrance guide 22, and is introduced between the fixing roller 1 and the pressure roller 6 of the fixing device A, as described in the above-mentioned <Example 1> to <Example 8>. After the image is fixed, the paper ejection guide 23 and paper ejection roller 2
4 and is output to a paper discharge tray 69 outside the machine.

Next, toner used in this electrophotographic apparatus will be explained.

When forming a color image or a full-color image, by using a sharp melt toner, the color reproduction range of the copy can be widened and a color copy that is faithful to the multicolor or full-color image of the original can be obtained.

The toner is manufactured by melt-kneading, pulverizing, and classifying toner-forming materials such as a binder resin such as a polyester resin or a styrene-acrylic ester resin, a colorant (dye, pigment, sublimable dye), and a charge control agent. Ru. If necessary, an external addition step of adding various external additives (for example, hydrophobic coloital silica) to the toner may be added.

In consideration of fixing properties and sharp melt properties, color toners using polystyl resin as a binder resin are particularly preferred. As the sharp melt polyester resin, a polymer compound having an ester bond in the main chain of a molecule synthesized from a diol compound and a dicarboxylic acid is exemplified.

In particular, the following formula (wherein R is an ethylene or propolene group and
are each a positive integer of 1 or more, and the average value of x and y is 2 to 10. A polyester resin cocondensed with at least a carboxylic acid component (e.g., fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) consisting of a substance or a lower alkyl ester thereof is sharp. It is more preferred because it has melting properties.

The softening point of the polyester resin is 75-150°C, preferably 80-120°C. FIG. 9 shows the softening properties of a toner containing polyester resin as a binder resin. The method for measuring the softening point in the present invention will be explained below.

Using a flow tester CFT-500A type (manufactured by Shimadzu Corporation), the diameter of the die (nozzle) is 0.2 mm and the thickness is 1.0 mm.
Add an extrusion load of 20 kg (mm) and set the initial temperature to 7.
After a preheating time of 300 seconds at 0° C., a toner plunger drop amount-temperature curve (hereinafter referred to as a softening S-curve) is determined when the temperature is raised at a constant rate of 6° C./min at 0° C.

The toner used as a sample is 1 to 3 g of precisely weighed fine powder, and the plunger cross-sectional area is 10 cm.

The softening S-shaped curve becomes a curve as shown in FIG.

As the temperature rises at a constant rate, the toner is gradually heated and begins to flow out (plunger descends A4B).

When the temperature is further increased, the molten toner largely flows out (B-+C-+D) and the plunger stops descending, ending the process (D-+E).

The height H of the S-shaped # line indicates the total outflow amount, and the temperature T0 corresponding to the six points of H/2 indicates the softening point of the sample (for example, toner or resin).

Whether the toner and the binder resin have sharp melt properties can be determined by measuring the apparent melt viscosity of the toner or the binder resin.

In the present invention, the toner or binder resin having sharp melting properties is defined as the temperature at which the apparent melt viscosity is 103 poise and T1.5X1o2 poise.
2, T, = 90 to 150°C 1△T l ” l Tl −T, I = 5
It refers to something that satisfies the conditions of ~20°C.

Sharp-melt resins having these temperature-melt viscosity characteristics are characterized by an extremely sharp decrease in viscosity when heated.

Such a viscosity reduction causes proper mixing of the uppermost toner layer and the lowermost toner layer, and also rapidly increases the transparency of the toner layer itself, resulting in good subtractive mixing.

Such sharp melt color toner has a high affinity and is easily offset to the fixing roller.

(Effects of the Invention) As described above, the fixing device of the present invention can prevent the occurrence of toner offset over a long period of time, and the intended purpose is well achieved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the configuration of an example of a fixing device according to the present invention. FIG. 2 is an explanatory diagram of offset toner removal from a nickel-plated web used as a cleaning member. FIG. 3 is a schematic diagram of the configuration of an example of a fixing device using a cleaning roller as a cleaning member. FIG. 4 is a perspective view of the cleaning roller. FIG. 5 is a schematic diagram of the configuration of an example of a fixing device in which the pressure roller is also provided with a cleaning device. FIGS. 6 and 7 are schematic diagrams of an example of a fixing device each equipped with a static eliminator. FIG. 8 is a schematic diagram of the configuration of an example of an image forming apparatus. FIG. 9 is a diagram showing the softening characteristics of color toner. FIG. 10 is a schematic diagram of the configuration of an example of a conventional fixing device. 1 is a fixing roller, 6 is a pressure roller, 17 and 17A are cleaning devices, 190 and 190A are nickel plated webs or cleaning rollers as conductive cleaning members, and BB/ is a bias application power source. Fig. 1 So and Fig. 6 Mow Fig. 7 Mow Fig.

Claims (5)

[Claims] (1) A fixing device including a rotating body that fixes an image in contact with a member carrying an unfixed toner image, a conductive cleaning member that contacts the rotary body and cleans the surface of the rotary body, and the conductive cleaning A fixing device comprising: means for applying a bias to a member. (2) The fixing device according to claim 1, wherein a bias having the same polarity as that of the toner is applied to the conductive cleaning member of the rotating body that is in contact with the image bearing surface of the member carrying the unfixed toner image. (3) A bias having a polarity opposite to that of the toner is applied to the conductive cleaning member of the rotating body that is in contact with the surface opposite to the image bearing surface of the member carrying the unfixed toner image. 2. The fixing device according to 2. (4) The fixing device according to claim 1, wherein a bias having a polarity opposite to that of the toner is applied to the conductive cleaning member of the rotating body. (5) The fixing device according to any one of claims 1 to 4, wherein the conductive cleaning member is a web plated with metal.