JP2003195674A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-priced fixing device providing a user with a stable cleaning effect. <P>SOLUTION: A rubber roller 14 having low frictional resistance is brought into press-contact with the fixing roller 5 of the fixing device T. Further, a rubber roller 13 similarly having low frictional resistance is brought into contact with the roller 14, and a cleaning roller 15 is brought into contact with the roller 13. In the rollers 13 and 14, gears provided on their respective rotary shafts are meshed with each other, and the driving shaft of the roller 13 is driven by a motor to be rotated, whereby the roller 14 is also rotated, and the toner on the roller 5 is stuck to the roller 14, fed to the rollers 13 and 15 whose temperature is becoming successively lower, and stuck and recovered to the roller 15. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided in a printer, a copying machine, a facsimile, etc.
More specifically, the present invention relates to a fixing device that fixes an unfixed image (an image formed by toner made of heat-meltable resin or the like) transferred onto a sheet, and more specifically, to a cleaning mechanism of the fixing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a laser beam printer, a developing device for developing a latent image drawn by laser light or the like, a transfer means for transferring the developed toner image to a sheet material, and a transfer device The one having a fixing device for fixing the formed toner image on a sheet material is mainly used. Among them, in a fixing device for fixing the transferred toner image on a sheet, a heater, a fixing roller that is driven and rotated while being kept at a predetermined temperature by a temperature sensor, and abutted on the fixing roller with a predetermined pressure. ,
A mainstream method is to fuse toner, which is a developer, with heat and pressure by a pressure roller that is driven to rotate and fix a toner image on a sheet material. As a cleaning mechanism of the fixing device, a pressure roller is often provided with a cleaning unit (cleaning roller or cleaning blade).

FIG. 7 shows a conventional laser beam printer as a typical example. The components of the laser beam printer of FIG. 7 will be described below.

In the printer body (image forming apparatus body) M, a laser scanner 12, a photosensitive drum 3 as an image carrier, a transfer roller 4, a fixing device T, and a conveying roller pair 1 are provided.
0, a paper feed cassette K, a paper feed roller (pickup roller) 1 and the like are installed.

A sheet-shaped recording material (hereinafter, simply referred to as "sheet material") S stacked and stored in a paper feed cassette K is fed by a paper feed roller 1 rotating in a clockwise direction, and a pair of registration rollers 2 is fed. It is sent to the nip.

Then, the sheet material S is a pair of registration rollers 2.
And is sent between the photosensitive drum 3 and the transfer roller 4.

The photosensitive drum 3 rotates clockwise, and an electrostatic latent image is sequentially formed on the outer peripheral surface of the photosensitive drum 3 by the laser light from the resist scanner 12. Subsequently, the electrostatic latent image is developed by a developing device (not shown). ), A toner image is formed. The toner image on the photosensitive drum 3 is sequentially transferred by the transfer roller 4 to the sheet material sent between the photosensitive drum 3 and the transfer roller 4.

The sheet material S on which the toner image has been transferred in this manner is sent to the fixing device T, where it is heated and pressed to fix the toner image on the sheet material S. After this, the sheet material S
Is sent to the discharge roller 10, and is then discharged onto the sheet material discharge tray 16 on the upper surface of the printer body by the discharge roller 10.

FIG. 8 is a detailed view of the fixing device of this conventional example. The configuration of the conventional fixing device will be described with reference to these drawings.

The fixing device T shown in FIG. 8 has the fixing roller 5 and the pressure roller 6 as a center, and a fixing frame 24 for supporting them, an entrance guide 27 integrally formed with the frame which serves as a guide for paper entry, and a paper discharge. The upper separation guide 25 serves as a guide for the mouth, the lower separation guide 26, and heaters 7 and 8 for heating the fixing roller and the pressure roller. Further, the fixing device T supplies electric power and delivers signals by connecting a connector (not shown) of the fixing device to a connector (not shown) on the main body side.

The fixing roller 5 and the pressure roller 6 are controlled to have predetermined temperatures by temperature sensors (not shown) provided respectively. Regarding the temperature, the temperature on the fixing roller 5 side with which the unfixed image is in contact is set higher than the temperature on the pressure roller 6 side.

The sheet material enters the fixing device T in the direction of arrow A from the entrance guide 27 side and is fixed at the nip portion between the fixing roller 5 and the pressure roller 6, and the separation upper guide 25 and the separation lower guide 26. The sheet is guided to the outside of the fixing device by the paper discharge roller pair 9.

In this conventional example, the pressure roller 6 is provided with a cleaning roller 17 for cleaning residual toner, dust and the like adhering to the surface of the pressure roller 6. The cleaning roller 17 is pressed in the direction of the pressure roller 6 by a pressure spring 28, supported by a bearing holder 29, and rotated by being driven by the pressure roller 6.

In such a fixing device, the toner first adheres to the fixing roller 5 with which the unfixed image is in contact. Since the toner is melted when it is in contact with a high surface temperature and adheres to the lower surface temperature side, the toner adhered to the fixing roller moves to the pressure roller 6 side where the temperature is lower and adheres to the cleaning roller 17 where the temperature is lower. . In this way, the residual toner is collected by the cleaning roller.

[0015]

As described above, in the conventional fixing device, the cleaning roller 17 is provided in order to prevent foreign matter (dust, toner) from adhering to the pressure roller 6.
Cleaning method is used.

However, the above-described conventional fixing device cleaning method has some problems to be solved. These are described below.

Problem 1. When there is a relationship among the fixing roller surface temperature> the pressure roller surface temperature> the cleaning roller surface temperature among the fixing roller surface temperature> the pressure roller surface temperature> the cleaning roller surface temperature, it is better that the toner is in contact with the higher surface temperature. As it melts and adheres to the side with the lower surface temperature, the residual toner can be collected with a cleaning roller.
Since the toner adheres to the surface of the cleaning roller, it is difficult to directly detect the temperature of the surface of the cleaning roller 17.

Therefore, when the sheet is continuously conveyed for a long time, the temperature difference between the cleaning roller surface temperature and the pressure roller surface temperature which is directly contacted with each other disappears, and the residual toner attached to the cleaning roller and collected is recovered. It adheres to the pressure roller again, and then adheres to the non-printing surface side of the conveyed sheet, which may stain the printed sheet.

Further, when printing is performed on both sides of the sheet, the printed surface becomes soiled, which makes the image unreadable, which is a disadvantage of being unusable as a printer.

In particular, when performing automatic double-sided printing, the sheet heated once by the fixing device is conveyed again to the fixing device, so that the temperature is immediately saturated and the backflow of the recovered toner is likely to occur.

Problem 2. Since the cleaning roller 17 is driven to rotate, if it is not pressed firmly against the pressure roller, it will slip and will not rotate smoothly, resulting in defective cleaning. Therefore, the residual toner has adhered to the sheet again.

If the cleaning roller 17 is strongly pressed to avoid this, the load for driving the fixing roller increases, and the gear for driving the fixing roller must be damaged and the torque of the motor for driving must be increased, resulting in an increase in cost. As a result, the motor became large and the image forming apparatus as a whole also became large.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a fixing device and an image forming apparatus which provide a user with a stable cleaning effect and a low cost.

[0024]

A first aspect of the present invention provides a roller pair in which a pressure roller is in contact with a fixing roller, and a cleaning means for cleaning the surface of either one of the roller pair. In the fixing device having a heater built in at least the fixing roller of the pair of rollers, the cleaning unit sequentially delivers the cleaning material that is collected by contacting one of the rollers of the pair of rollers. It is characterized in that a plurality of cleaning material conveying members each having an elastic body having a small surface resistance to be sent to are arranged in rows.

According to a second aspect of the present invention, a roller pair in which a pressure roller is in contact with the fixing roller, a heater incorporated in at least the fixing roller of the roller pair, and one of the roller pair are provided. In the fixing device having a cleaning unit for cleaning the surface of the roller, the cleaning unit transfers the cleaning material collected by contacting any one of the pair of rollers to the cleaning member and having a small surface resistance. It has a cleaning material conveyance member which has.

According to a third aspect of the invention, an image forming means for forming a toner image on the image carrier and carrying an unfixed toner image on the image carrier on a recording material, and the image forming means. An image forming apparatus having any one of the above fixing devices for fixing an unfixed toner image.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus and a fixing apparatus according to the present invention will be described in detail below with reference to the embodiments shown in the drawings. 1 to 6, the same members as those in the conventional example shown in FIGS. 7 and 8 are designated by the same reference numerals, and the description thereof will be omitted. Further, since the basic configuration of the image forming apparatus in the embodiment is the same as that of the conventional image forming apparatus shown in FIG. 7, detailed description of the entire image forming apparatus and its functions will be omitted.

(Embodiment 1) FIG. 1 is a sectional view of an image forming apparatus provided with a fixing device according to Embodiment 1 of the present invention.

The fixing device T in this embodiment is provided so that the cleaning device C is in contact with the fixing roller 5.

The structure of the cleaning device C will be described below with reference to FIGS.

Reference numerals 13 and 14 denote rollers as cleaning material conveying members, which have a known coating (for example, fluorine coating) on the surface of a roller in which a silicone rubber as an elastic body is wound around a metal core bar to reduce frictional resistance. is there. A cleaning roller 15 is in pressure contact with the rubber roller 13.

In FIG. 2, 19 is a rubber roller 13, 1.
4, a cleaning roller 15 and the like.

The axes of the rubber rollers 13 and 14 are determined by the frame 19, and the rubber rollers 13 and 14 are constructed in consideration of thermal expansion so that the surfaces of the rubber rollers come into light contact with each other when thermally expanded.
The cores of the rubber rollers 13 and 14 are held by the frame 19 via bearings and are rotatable. The cleaning roller 15 is pressed against the rubber roller 13 by a spring 30 via a bearing 29. Then, the rubber roller 13
Rotates following the rotation of. Both ends of the spring 30 are hooked on the spring hooks 19a and 19b of the frame 29, respectively.

The frame 19 can be swung around the shaft 13a of the rubber roller 13, and the roller 14 is constantly in pressure contact with the fixing roller 5 by the spring 20.

FIG. 3 is a detailed view of the drive unit of the cleaning device.

In the figure, 21 is a gear driven by the rotation of the rubber roller 13, and 22 is a gear meshed with the gear 21 to transmit the drive. When the gear 22 rotates, the drive is transmitted to the rubber roller 14. Here, even if the rollers 13 and 14 are rotated by the gears, the rollers 13 and 14 are rotated.
Since and 14 are lightly contacted, no unreasonable force is applied to the gear and the roller surface.

FIG. 4 is a top view of the cleaning device.
In the figure, 23 is a gear holding the one-way clutch 23a. When a driving force in a predetermined direction is transmitted from the motor (not shown) to the gear 23, the one-way clutch 2
The rotation is transmitted to the rubber roller 13 via 3a, and further the rotation is transmitted to the rubber roller 14 via the gears 21 and 22.

The printing operation of this embodiment will be described with reference to these figures.

Returning to FIG. 1, the sheet materials S stacked and stored in the paper feed cassette K are
The sheet is fed by the sheet feeding roller 1 rotating in the clockwise direction and is fed to the nip portion of the registration roller pair 2. Next, the sheet material S is sent between the photosensitive drum 3 and the transfer roller 4 by the registration roller pair 2. The photosensitive drum 3 rotates clockwise, and an electrostatic latent image is sequentially formed on the outer peripheral surface of the photosensitive drum 3 by the laser light from the laser scanner 12. Subsequently, the electrostatic latent image is developed by a developing device (not shown). , A toner image is formed.

The toner image on the photosensitive drum 3 is sequentially transferred by the transfer roller 4 to the sheet material sent between the photosensitive drum 3 and the transfer roller 4. The sheet material S on which the toner image has been transferred in this manner is sent to the fixing device T, where it is heated and pressed to fix the toner image on the sheet material S. After that, the sheet material S is sent to the discharge roller 10, and is then discharged by the discharge roller 10 onto the sheet material discharge tray 16 on the upper surface of the image forming apparatus main body.

Next, the structure of the fixing device according to the first embodiment will be described with reference to FIGS.

In FIG. 4, when the driving force is transmitted to the gear 23 by the driving source from the outside of the fixing device as described above, the driving force is transmitted to the rubber roller shaft 13a via the one-way clutch 23a to rotate the rubber roller 13. When the rubber roller shaft 13a rotates, the rubber rollers 14 are rotated by the gears 21 and 22.

Continuing the explanation with reference to FIG. 2, the rubber roller 13 to which the rotation is transmitted in the clockwise direction by the one-way clutch 23a gives the rotation in the counterclockwise direction to the rubber roller 14 by the gears 21 and 22, and the rubber roller 14 rotates. While the fixing roller 5 is being driven and rotated, the spring 20
The rotation speed of the surface of the fixing roller 5 and the rotation speed of the surface of the rubber roller 14 which are pressed against each other are the same or slightly higher than the rotation speed of the surface of the fixing roller 5.

Since the fixing roller 5 and the rubber roller 14 are in pressure contact with each other, the rubber roller 14 is rotated by the rotation of the fixing roller 5, and the gears 21 and 22 rotate the shaft 13a.
This is to prevent an unreasonable force from being applied to the gear train by causing the one-way clutch 23a to slide even if the rotation is transmitted to the gear train.

The surface temperature of the rubber roller 14 is slightly lower than the surface temperature of the fixing roller 5 (predetermined fixing temperature), the surface temperature of the rubber roller 13 is lower, and the temperature of the cleaning roller 15 is lower.

Continuing the explanation with reference to FIG. 2, when the toner adheres to the surface of the fixing roller 5 in contact with the unfixed image, the toner adheres to the surface of the rubber roller 14 which is driven to rotate and has a low temperature and a small surface friction resistance. Rubber roller 1 with lower temperature
3 and then finally adheres to the cleaning roller 15 having the lowest temperature. In this way, the residual toner is collected by the cleaning roller.

(Modification of First Embodiment) FIG. 5 shows a modification of the first embodiment. In order to further enhance the cleaning effect in the above-described first embodiment, image formation having means for cooling the cleaning roller 15 is performed. Shows the device.

In FIG. 5, numeral 31 indicates a fan for blowing air. As shown in the figure, the cleaning roller 15 is arranged in an inclined state, and a part thereof projects and is exposed from an opening T1 formed in the upper portion of the exterior member of the fixing device. For this reason, since it contacts the air passage created by the fan 31, it is further cooled and the temperature does not rise, so that the residual toner collected by the cleaning roller does not flow back.

With the above structure, the following effects can be obtained in this embodiment.

1) Since a plurality of rubber rollers (13, 14) are provided from the cleaning roller 15 to the fixing roller which is a heat source, the cleaning roller 15 is hard to warm and the residual toner attached and collected on the cleaning roller 15 is again fixed to the fixing roller. There is no backflow to the side.

2) Since the rubber rollers 13 and 14 for adhering the residual toner on the surface of the fixing roller 5 to the cleaning roller 15 are rotationally driven by the gears, the residual toner on the surface of the fixing roller surely moves to the rubber roller 14, Further, the toner collected by the rubber roller 14 surely moves to the rubber roller 13. This allows the cleaning roller 15 to reliably collect the toner.

3) Since the rubber roller 14 in contact with the fixing roller 5 is rotationally driven, the force of the spring 20 in pressure contact can be set weakly and does not become a driving load for the fixing roller. As a result, the drive gear train that drives the fixing roller is not damaged, and the output of the motor that drives the fixing roller 15 does not need to be large, so that it is not necessary to enlarge the device.

4) Since the cleaning roller 15 is brought into contact with the air passage, it can be cooled further, and the above-mentioned backflow of the residual toner can be further prevented.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention. The components having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 33 denotes a rubber roller as a cleaning material conveying roller made of rubber, which is an elastic material whose surface is coated with Teflon (registered trademark), 32 denotes a cleaning roller, and the rubber roller 33 is in contact with the pressure roller 6. The cleaning roller 32 is in contact with the rubber roller 33. A part of the cleaning roller 32 projects and is exposed from an opening T2 provided at the bottom of the exterior member of the fixing device, and is exposed to the (fixing) atmosphere.

Continuing the description with reference to FIG. 8, the residual toner attached to the fixing roller 5 is attached to the pressure roller 6 having a low temperature, and further attached to the rubber roller 33 having a low temperature. Then, it adheres to the cleaning roller 32 having a lower temperature. In this way, the cleaning roller 32 collects the pressure roller 6, the rubber roller 33, and the plurality of rollers.

Since the cleaning roller 32 is in contact with the fixing roller 5 via a plurality of rollers, the temperature is unlikely to rise, and since it is in contact with the air outside the fixing device, the temperature is less likely to rise.

As described above, according to the present embodiment, the residual toner attached and collected on the cleaning roller 32 does not flow back to the fixing roller side again.

[0059]

As described above, according to the present invention, the following effects can be obtained.

1) Since the cleaning roller as the cleaning member is in contact with the fixing roller as the heat source or the pressure roller via the plurality of or one roller as the cleaning material conveying member, it is hard to be warmed, and thus the cleaning roller is The residual toner adhered and collected does not flow back to the fixing roller or the pressure roller side again.

2) By rotating at least one of the plurality of rubber rollers positioned between the cleaning roller as a cleaning member and the fixing roller (or the pressure roller), the fixing roller surface remains, for example. The toner can be reliably transferred to the rubber roller, and the toner can be reliably collected by the cleaning roller.

3) Since the rubber roller that is in contact with the fixing roller is rotationally driven, the pressure contact force that is in pressure contact can be set weakly and does not become a drive load for the fixing roller. As a result, for example, the gear train constituting the drive mechanism for driving the fixing roller is not damaged, and the output of the motor for driving the fixing roller does not need to be increased, so that the device does not need to be enlarged.

4) Since the cleaning roller is brought into contact with the air passage, it can be cooled further and the above-mentioned backflow of the residual toner can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing an image forming apparatus including a fixing device according to a first embodiment of the present invention.

FIG. 2 is a detailed view showing a cleaning mechanism portion of the fixing device of FIG.

FIG. 3 is a detailed view showing a drive unit of the cleaning mechanism unit of FIG.

FIG. 4 is a top view showing a drive unit of the cleaning mechanism unit of FIG.

FIG. 5 is a sectional view of a fixing device showing a modified example of the first embodiment of the invention.

FIG. 6 is a sectional view of a fixing device according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view showing an image forming apparatus including a conventional fixing device.

FIG. 8 is a sectional view of the fixing device in FIG.

[Explanation of symbols] 1 Feed roller 2 Registration roller pair 3 photosensitive drum 4 Transfer roller 5 fixing roller 6 pressure roller 7 heater 8 heater 9 Conveyor roller pair 10 Discharge roller 11 mirror 12 scanner 13, 14 Rubber roller 15 Cleaning roller 16 Ejection tray 17 Cleaning roller 19 Frame that holds the cleaning mechanism 20 springs 21 gears 22 gears 23 gears 23a One-way clutch 24 fixing frame 28 springs 29 bearings 30 springs 31 Air blower fan 32 cleaning roller 33 rubber roller M image forming apparatus K cassette S sheet

Claims (12)

[Claims] 1. A roller pair in which a pressure roller is in contact with a fixing roller, and cleaning means for cleaning the surface of either one of the roller pair, and at least the roller pair of the roller pair. In a fixing device in which a heater is built in a fixing roller, the cleaning unit has an elastic body having a small surface resistance, which sequentially delivers the cleaning material that has come into contact with one of the rollers of the roller pair and is collected to a cleaning member. A fixing device in which a plurality of cleaning material conveying members are arranged in a row. 2. The fixing device according to claim 1, wherein the cleaning material conveying member is formed in a roller shape. 3. A drive mechanism for rotationally driving the plurality of cleaning material carrying members by a driving force from a driving source,
The fixing device according to claim 1, wherein the cleaning material conveying member is brought into contact with the roller surface of one of the roller pairs while rotating. 4. The drive mechanism according to claim 3, wherein the drive mechanism has a clutch means for preventing rotation from one of the rollers of the roller pair from being transmitted to the drive source side. Fixing device. 5. The fixing roller according to claim 1, wherein one of the rollers of the roller pair is the fixing roller.
The fixing device according to any one of 1. 6. The fixing device according to claim 1, wherein the cleaning member is formed in a roller shape. 7. A roller pair in which a pressure roller is in contact with a fixing roller, a heater incorporated in at least the fixing roller of the roller pair, and a surface of either one of the roller pair is cleaned. In the fixing device having a cleaning unit for cleaning the cleaning unit, the cleaning unit has an elastic body having a small surface resistance for transferring the cleaning material collected by contacting any one of the pair of rollers to a cleaning member. A fixing device having a conveying member. 8. The fixing device according to claim 7, wherein one of the rollers of the roller pair is the pressure roller. 9. The fixing device according to claim 1, wherein the elastic body having a small surface resistance is a silicone rubber surface having a fluorine coating. 10. The fixing device according to claim 1, wherein the cleaning member is exposed from an opening formed in an exterior member of the fixing device. 11. An image forming unit for forming a toner image on an image carrier and carrying an unfixed toner image on the image carrier on a recording material, and an unfixed toner image carried on the recording material. An image forming apparatus comprising: the fixing device according to any one of claims 1 to 10 for fixing the image forming apparatus. 12. An image forming unit for forming a toner image on an image carrier and carrying an unfixed toner image on the image carrier on a recording material, and an unfixed toner image carried on the recording material. An image forming apparatus, comprising: the fixing device according to claim 9 for fixing a toner image; and an air blower configured to blow cooling air to the cleaning member exposed from an opening of an exterior member of the fixing device.