JP2001142310A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device preventing the occurrence of rolling-in of toner removing means (so-called blade rolling-in) consisting of an elastic body and cleaning defect, and making adaptable to a cleaning roller of a small diameter, too. SOLUTION: The image forming device is provided with a photoreceptor 14 carrying the toner image, a transfer belt 23 transporting in carrying transfer paper P so as to be allowed to pass through a transfer positions S facing the photoreceptor 14, a cleaning roller 28 consisting of a metallic material being held in contact with the transfer belt 23 surface for cleaning the surface thereof, forming the toner image on the photoreceptor 14 by an effect of voltage applied on the transfer belt 23, a scraper member 40 consisting of metallic material being held in contact with the cleaning roller 28 for removing the toner from the surface thereon.

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 such as a copying machine, a facsimile, a printer and the like, and more particularly, to an image carrier for carrying a toner image, and an endless belt opposed to the image carrier. And a cleaning roller made of a metal material that contacts the surface of the endless belt to clean the surface, and a toner image formed on the surface of the image carrier by the action of a voltage applied to the endless belt. The present invention relates to an image forming apparatus that transfers a toner image to a transfer material surface at a transfer position.

[0002]

2. Description of the Related Art Conventionally, as a transfer device of an image forming apparatus of this type, a transfer belt is used to carry a transfer material by carrying a transfer belt so as to pass a transfer position facing an image carrier on which a toner image is formed, and transfer the transfer material. When the material passes through the transfer position, a predetermined transfer electric field is generated at the transfer position, and the transfer electric field causes the toner image on the image carrier to be transferred to the transfer material side, and the toner remaining on the transfer belt surface after the transfer. Is known by using a cleaning means. As this cleaning means, a system in which a cleaning blade is directly brought into contact with a transfer belt is generally used.

However, in the cleaning method using a cleaning blade, a mechanical load is applied due to the cleaning blade directly contacting the transfer belt, and the transfer belt is easily deteriorated with time. Further, cracks and the like are easily generated on the surface of the transfer belt due to expansion and contraction caused by winding and rotation of the transfer belt. As a result, poor cleaning of the transfer belt tends to occur. In addition, the transfer belt is required to have very advanced functions in electrophotographic technology, such as transfer of a toner image from an image carrier to a transfer material, conveyance of an unfixed transfer material, and the like. Has characteristics. For this reason, it is difficult to provide the transfer belt with characteristics necessary for preventing poor cleaning, and it is not preferable to apply a mechanical load to the transfer belt.

Therefore, instead of directly contacting the cleaning blade as a toner removing means with the transfer belt,
A cleaning roller method in which a cleaning roller is brought into contact has been proposed. For example, in JP-A-6-59586, a metal conductive cleaning roller is brought into contact with the surface of a transfer belt to remove residual toner on the surface, and the surface of the cleaning roller is made of polyethylene terephthalate (PE).
An image forming apparatus has been proposed in which a blade made of an elastic material made of T) or rubber is brought into contact to remove residual toner on the surface. In this image forming apparatus, since the toner adhered to the transfer belt is electrically removed by the cleaning roller, almost no mechanical load is applied to the transfer belt.

[0005]

However, when a blade made of an elastic material such as polyurethane rubber, which is conventionally used, is brought into contact in the counter direction, the cleaning roller and the blade may be displaced due to variations in the tip position and angle of the blade. The variation in the cleaning angle increases.
As a result, either cleaning failure or blade entrainment is likely to occur. Further, if the accuracy of each component is increased in order to avoid these problems, the cost increases. Therefore, the diameter of the cleaning roller has to be increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the involvement of a toner removing means made of an elastic material (so-called blade involvement).
It is an object of the present invention to provide an image forming apparatus which can prevent occurrence of cleaning and defective cleaning and can cope with a small-diameter cleaning roller.

[0007]

According to one aspect of the present invention, there is provided an image bearing member for carrying a toner image, an endless belt opposed to the image bearing member, and an endless belt. A cleaning roller made of a metal material that abuts on the surface of the endless belt to clean the surface, and transfers a toner image formed on the surface of the image carrier at a transfer position by the action of a voltage applied to the endless belt. An image forming apparatus for transferring to a surface of a material is characterized in that a toner removing means made of a metal material which contacts the surface of the cleaning roller and removes toner from the surface is provided.

In the image forming apparatus according to the first aspect, when the toner removing means is brought into direct contact with the cleaning roller and the surface is mechanically cleaned, the toner removing means is made of a metal material, and thus is made of an elastic material. Entanglement as occurs in the toner removing means does not occur. Also, as a result, the margin for setting the cleaning angle increases,
It can also be used for small diameter cleaning rollers. Furthermore, when mechanically cleaning the cleaning roller, the cleaning performance can be improved because the ease of cleaning that could not be added to the endless belt can be added to the characteristics of the cleaning roller.

In a second aspect of the present invention, in the image forming apparatus of the first aspect, the toner removing means is in contact with a surface of the cleaning roller from a counter direction.

In the image forming apparatus of the present invention, a counter system is employed in which the tip of the toner removing means extends toward the upstream side in the rotation direction of the cleaning roller and comes into contact with the cleaning roller near the tangential direction. As compared with the trading method in which the tip of the scraper extends toward the downstream side in the rotation direction of the cleaning roller and comes into contact with the peripheral surface of the cleaning roller from near the vertical direction, the cleaning performance is improved and a small space is required. .

According to a third aspect of the present invention, in the image forming apparatus of the first aspect, a voltage having the same polarity or opposite polarity to the electric field applied to the transfer position is applied to the cleaning roller. It is assumed that.

In the image forming apparatus of the third aspect, a voltage is applied to the cleaning roller in order to electrically remove toner remaining on the endless belt. When removing the toner charged to the normal polarity, a voltage having a polarity opposite to the voltage applied to the transfer position is applied. However, since there is also a toner charged with a polarity opposite to the normal charging polarity, when removing the toner, a voltage having the same polarity as the voltage applied to the transfer position is applied. As a result, the toner remaining on the endless belt is completely removed regardless of the charging polarity of the toner.

According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, the voltage is applied to the cleaning roller via the toner removing unit.

In the image forming apparatus according to the fourth aspect, a voltage can be directly applied to the surface of the cleaning roller via the toner removing means made of a metal material. There is no need to provide a contact.

According to a fifth aspect of the present invention, in the image forming apparatus of the first aspect, the surface of the cleaning roller is subjected to a soft nitriding treatment.

In the image forming apparatus according to the present invention, the surface of the cleaning roller is subjected to a soft nitriding treatment to improve the slidability and the surface hardness of the surface. Also exhibits excellent durability for cleaning.

According to a sixth aspect of the present invention, in the image forming apparatus of the first aspect, the cleaning roller has a Vickers hardness (load: 0.1 kg) of Hv 800 or more.

In the image forming apparatus according to the present invention, the surface hardness of the cleaning roller is determined by Vickers hardness (load: 0.1).
Hv is 800 or more at 1 kg) to improve the durability of the cleaning roller.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an image forming apparatus to which the present invention is applied will be described. First, the configuration and operation of the entire image forming apparatus will be described. FIG. 1 is a front view illustrating a schematic configuration of the entire image forming apparatus. The image forming apparatus shown here has a copy function and a printer function for reading an original and forming an image by an electrophotographic method based on the original image, and further adds a function as a facsimile. You can also. In FIG. 1, the image forming apparatus includes a photosensitive member 1 as an image carrier.
4, a developing device 16 for forming a toner image on the surface of the photoreceptor 14, a transfer device 22 for transferring and transferring the toner image on the surface of the photoreceptor 14 to a transfer paper P as a transfer material, and a transfer device 2.
A belt cleaning device 26 that removes toner adhered to the surface of the transfer belt 23 as the endless belt 2 and cleans the surface of the transfer belt 23; a fixing device 30 that fixes the toner image transferred to the transfer paper P; A photoconductor cleaning device 33 that cleans the surface of the photoconductor 14 after transferring the toner image onto the transfer paper P;

A document (not shown) placed on a contact glass 2 fixed on an upper portion of the image forming apparatus main body 1 is illuminated by a light source 3 moving rightward in FIG. The light is reflected by the first mirror 4 moving to the right together with the light source 3 and then reflected by the second mirror 5 and the third mirror 6 which move right one light at half the speed of the light source 3 and read. The light enters the device 7. The reading device 7 has an image sensor (not shown) formed of, for example, a CCD for reading a reflected light image from a document, and an imaging lens (not shown) for forming an optical image on the sensor. Then, the image signal read by the reading device 7 is sent to the exposure device 8. The exposure device 8 includes a rotary polygon mirror 9 for reflecting a laser beam L emitted from a laser light source (not shown), and a mirror 11 for reflecting the laser beam L passing through a scanning imaging lens system 10 including an fθ lens and the like. , 12 and 13, and irradiates the surface of the photoreceptor 14 with a laser beam L light-modulated in accordance with the image signal read by the reading device 7 so that the surface of the photoreceptor 14 has an electrostatic capacity corresponding to the image original. Form a latent image.

The electrostatic latent image described above is
Is visualized as a toner image. The developing device 16 shown in FIG. 1 includes a developer case 18 containing a developer D and a developing roller 17 rotatably supported inside the developer case 18.
And transports and carries the developer D on the peripheral surface of the developing roller 17 which is driven to rotate.
The electrostatic latent image formed in No. 4 is visualized as a toner image. In the developing device 16, a powdery two-component developer having a toner and a carrier is used as the developer D, but a one-component developer not containing a carrier may be used. Further, a toner supply container 18A is attached to the developer case 18, and the toner T is stored therein. Developer case 1
When the toner concentration of the developer D in the toner cartridge 8 decreases, the toner supply roller 19 rotates to supply the toner T in the toner supply container 18A into the developer D in the developer case 18.

On the other hand, a plurality of paper cassettes 20, 20A,
The transfer paper P stored in one of the cassettes 20B is
The sheet is fed in the direction of arrow A, and is fed to the transfer device 22 by the pair of registration rollers 21. Next, the transfer device 22 will be described in detail. FIG. 2 is a front view showing a schematic configuration of the transfer device 22, the belt cleaning device 26, and the fixing device 30. The transfer device 22 rotatably supports a drive roller 24A, a driven roller 24B, and a bias roller 25 around which a transfer belt 23 is wound around a case 27. The transfer belt 23 is formed of a material whose surface resistivity in contact with the transfer paper P has an electrically medium resistance and is driven by a driving roller 24A, a driven roller 24B, and a bias roller 25 so as to move in the direction of arrow B. It is wound around and is in contact with the surface of the photoconductor 14 at the transfer position S. When the transfer material P passes through the transfer position S, the high-voltage power supply 50
Thus, an electric field having a polarity opposite to that of the toner is applied to the bias roller 25. When a voltage is applied to the bias roller 25, the bias roller 25
Current flows through the transfer belt 23 to the drive roller 24A and the driven roller 24B, and further flows to the photoconductor 14 via the transfer paper P. The applied voltage at this time is such that the current flowing through the photoconductor 14 is a predetermined value (a− (b +
c) = transfer current). The transfer belt 23 is charged once by the bias roller 25 to which the voltage is applied, but is discharged by the driving roller 24A.

In the transfer device 22 configured as described above, the transfer paper P sent out by the pair of registration rollers 21 is aligned with the toner image on the photoreceptor 14 while being carried and conveyed by the transfer belt 23. At a timing, the sheet passes through the transfer position S between the transfer belt 23 and the photoconductor 14. At this time, a voltage having a polarity opposite to the charging polarity of the toner on the photoreceptor 14 is applied to the bias roller 25 disposed on the back side of the transfer belt 23, and the toner image on the photoreceptor 14 is transferred to the surface of the transfer paper P. It is electrostatically transferred. The transfer paper P on which the toner image has been transferred is continuously carried on the transfer belt 23 and conveyed. After leaving the transfer belt 23, the transfer paper P is fed to the fixing device 30. In the fixing device 30, the transfer paper P passes between the heating roller 30A and the pressure roller 30B, and the toner image is fixed on the transfer paper P by the action of heat and pressure. Next, the transfer paper P is discharged to the discharge tray 32 as copy paper by the pair of discharge rollers 31.

The transfer residual toner that has not been transferred to the transfer paper P adheres to the surface of the photoreceptor 14 after the transfer of the toner image. The transfer residual toner on the surface of the photoconductor 14 is removed by the photoconductor cleaning device 33. The photoconductor cleaning device 33 includes a cleaning blade 34.
And a cleaning case 35, and a toner discharging member 36 disposed at the bottom of the cleaning case 35. The cleaning blade 34 is made of an elastic material such as rubber, and extends in parallel to the photoconductor 14 over the entire image area in the axial direction of the photoconductor 14, that is, the area where the transfer residual toner adheres. Is fixed to the cleaning case 35, and the leading edge opposite to the cleaning case 35 is pressed against the surface of the photoconductor 14 to scrape and remove transfer residual toner attached to the surface of the photoconductor 14. Further, the surface of the photoreceptor 14 after cleaning is initialized by being subjected to a charge removing operation by a charge removing device 37 composed of a lamp, and further charged by a charging device 15 in a similar manner. Then, the above-described operation is continuously performed, and the toner image newly formed on the surface of the photoconductor 14 is transferred onto the next transfer paper P.

Further, some background toner on the photoreceptor 14 is transferred and adheres to the surface of the transfer belt 23 as well.
If left unattended, the toner adheres to the back surface of the transfer paper P sent to the transfer belt 23, and the transfer paper P is stained with the toner. The toner adhered to the surface of the transfer belt 23 is transferred to the belt cleaning device 2 described below.
6 removed.

Next, a description will be given of the belt cleaning device 26 which is a feature of the present invention. The belt cleaning device 26 includes a cleaning roller 28 that presses against the surface of the transfer belt 23 to remove toner from the surface and a scraper member 40 that contacts the cleaning roller 28 and removes toner from the surface. Have. The cleaning roller 28 is made of a conductive metal material, is disposed parallel to the transfer belt 23 over the entire area of the transfer belt 23 to which toner adheres, and is a gear (not shown) attached to the drive roller 24A. ) And a gear (not shown) attached to the cleaning roller 28 mesh with each other, so that the transfer belt 23 rotates in the same direction. As shown in FIG. 3, the scraper member 40 has an L-shaped base 40-a and a holder 40-.
b and a thin plate-shaped scraper 40-c, all of which are made of a metal material and can be conducted. The scraper member 40 is arranged in parallel with the cleaning roller 28 over the entire area of the cleaning roller 28 where the toner adheres, and includes a base 40-a, a holder 40-b, and a base end of the scraper 40-c. Are attached to the mounting table 41. The other end of the scraper 40-c contacts the surface of the cleaning roller 28 from the counter direction so as to extend toward the upstream side in the rotation direction of the cleaning roller 28. Generally, in the counter method, the tip of the scraper 40-c is
Since the scraper is brought into contact near the tangential direction of 8, the cleaning performance is improved and a small space is required as compared with the trading method in which the tip of the scraper comes into contact with the cleaning roller near the vertical direction.

A voltage is applied to the cleaning roller 28 from the high-voltage power supply 50 so as to have a predetermined potential difference with respect to the driving roller 24A. The voltage is applied to the cleaning roller 28 via the scraper member 40.
The cleaning is performed directly on the surface of the cleaning roller 28. Specifically, as shown in FIG. 3, the harness 5 is attached to the holder 40-b.
The harness 51 is connected to the high-voltage power supply 50 shown in FIG. Thus, a voltage is applied to the cleaning roller 28 via the scraper member 40.

In the belt cleaning device 26 configured as described above, the toner on the transfer belt 23 is
The toner that has adhered to the cleaning roller 28 to which the voltage has been applied and that has adhered to the cleaning roller 28 is mechanically scraped off by the scraper member 40. Then, the toner scraped off by the scraper member 40 is transferred to the cleaning case 27 constituted by the above-described case 27.
A is discharged by a toner discharge member 29 arranged at the bottom of A.

The polarity of the toner that can be cleaned differs depending on the potential difference of the cleaning roller 28 with respect to the driving roller 24A. Transfer belt 23
The polarity of the toner present on the upper side is not limited to that of the normal charging polarity, and there is also the polarity of the opposite polarity. Therefore, it is preferable that not only a voltage of the opposite polarity to the voltage applied at the transfer position S but also a voltage of the same polarity be applied to the cleaning roller 28. For example, the transfer position S
The belt cleaning device 26 may be provided with a control means capable of appropriately applying a voltage having the opposite polarity or the same polarity as the voltage applied in the step (a). Further, a plurality of cleaning rollers 28 having the above-described functions may be provided, or the above-described cleaning operation may be performed a plurality of times. Thereby, the cleaning property can be improved.

The cleaning roller 28 is preferably made of stainless steel (SUS) subjected to soft nitriding. By performing the soft nitriding treatment, the slidability of the surface of the cleaning roller 28 is improved, and at the same time, the surface hardness is increased and the durability is improved. Specifically, the surface hardness of the cleaning roller 28 is preferably Vv800 hardness (load: 0.1 kg) Hv 800 or more from the viewpoint of durability.

[0031]

According to the first to sixth aspects of the present invention, there is no occurrence of entangling of the toner removing means made of an elastic body (so-called entangling of the blade), so that the margin for setting the cleaning angle is increased. Therefore, there is an excellent effect that the diameter of the cleaning roller can be reduced, and the size of the apparatus can be reduced. In addition, since it is possible to add ease of cleaning to the characteristics of the cleaning roller,
There is an excellent effect that the cleaning performance is improved.

In particular, according to the second aspect of the present invention, there is an excellent effect that the cleaning performance is improved and the size of the apparatus can be reduced as compared with the case where the contact is made in the trading direction.

According to the third aspect of the present invention, there is an excellent effect that the toner remaining on the endless belt can be completely cleaned regardless of the charging polarity of the toner.

According to the fourth aspect of the present invention, there is no need to provide a dedicated contact for applying a voltage to the cleaning roller, so that there is an excellent effect that the cost can be reduced.

According to the fifth and sixth aspects of the present invention, since the slidability and surface hardness of the cleaning roller surface are improved and the durability is excellent, the cleaning performance is maintained for a long time, and the life of the apparatus is extended. There is an excellent effect that it can be achieved.

[Brief description of the drawings]

FIG. 1 is a front view illustrating a schematic configuration of an image forming apparatus according to an embodiment.

FIG. 2 is a front view illustrating a schematic configuration of a transfer device and a belt cleaning device of the image forming apparatus.

FIG. 3 is an enlarged perspective view of a main part showing a schematic configuration of the belt cleaning device.

[Explanation of symbols]

 Reference Signs List 14 photoconductor 22 transfer device 23 transfer belt 26 belt cleaning device 28 cleaning roller 40 scraper member 30 fixing device 33 photoconductor cleaning device 50 high-voltage power supply P transfer paper S transfer position

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Saito 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H032 AA05 BA05 BA18 BA23 BA30

Claims (6)

[Claims] An image bearing member for carrying a toner image, an endless belt opposed to the image bearing member, and a cleaning roller made of a metal material which contacts the surface of the endless belt to clean the surface. An image forming apparatus that transfers a toner image formed on the surface of the image carrier to the surface of a transfer material at a transfer position by the action of a voltage applied to the endless belt. An image forming apparatus comprising: a toner removing unit made of a metal material that removes toner from a surface. 2. The image forming apparatus according to claim 1, wherein said toner removing means is in contact with a surface of said cleaning roller from a counter direction. 3. The image forming apparatus according to claim 1, wherein a voltage having the same polarity or opposite polarity to an electric field applied to the transfer position is applied to the cleaning roller. 4. An image forming apparatus according to claim 3, wherein said voltage is applied to said cleaning roller via said toner removing means. 5. The image forming apparatus according to claim 1, wherein the surface of said cleaning roller is subjected to a soft nitriding treatment. 6. The image forming apparatus according to claim 1, wherein the cleaning roller has a Vickers hardness (load: 0.1 kg) of Hv 800 or more.