JPH08314347A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device equipped with a new cleaning device capable of securing an allowance of cleaning ability with reference to toner whose mean grain size distribution is <=7μm and spherical toner, and also capable of reducing, or preventing vibration in an image forming system. CONSTITUTION: The cleaning device 10 is constituted by using an elastic roller member 120 installed so as to come into contact with the surface of a photoreceptor drum 1 and so as to be freely rotated accompanying with the movement of the surface of the drum 1 and a potential difference forming means for forming a prescribed potential difference between the roller member 120 and the photoreceptor drum 1. On the surface part of the elastic roller member 120, a conductive roller-like part 120a made of elastic material with a prescribed resistance is formed, and an insulating roller-like part 120b made of insulating elastic material is formed so as to be positioned outside both ends of the part 120a.

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 and a printer, and more specifically, to a latent image after transfer in a transfer type image forming apparatus using an electrophotographic system or an electrostatic recording system. The present invention relates to an improvement of a cleaning device that removes residual toner on an image carrier.

[0002]

2. Description of the Related Art Conventionally, in a transfer type image forming apparatus of this type, a latent image is formed by exposing a document image on, for example, a photoconductor as a latent image carrier uniformly charged by a charger. Then, a toner is attached to the latent image by a developing device to make it visible as a toner image. This toner image is transferred to a transfer paper or an intermediate transfer medium by a transfer device. Then, the toner remaining on the photoconductor after the transfer is removed from the photoconductor by the cleaning device, and the photoconductor is continuously and repeatedly used.

This cleaning device has a cleaning device using a cleaning blade, a cleaning device using a far brush roller made of conductive or insulating fibers, and a polishing ability. A cleaning device using a cleaning roller, a cleaning device using a cleaning roller containing a lubricant substance therein, and a magnetic brush roller having magnetic powder on the surface of the roller. Various types of cleaning devices such as a cleaning device used and a cleaning device using an aspirator are known.

However, in any of the above-mentioned methods, a cleaning ability margin is provided for toner or spherical toner having an average particle size distribution of 7 μm or less which is considered to be used for high image quality. It is difficult to secure the degree.

In addition, the toner is easily scattered, and it is difficult to reduce or prevent the vibration in the image forming system, which is the most problematic in realizing the high density reproduction which has recently been demanded. There are many.

For example, a so-called far brush cleaning in which a far brush roller composed of conductive fibers or insulating fibers is rotated and brought into contact with the surface of the photoconductor to clean residual toner on the photoconductor. In a cleaning system of the type, toner scattering easily occurs as the far brush roller rotates. In addition, a cleaning roller with polishing ability
The roller is brought into contact with the surface of the photoconductor, and is rotationally driven so as to have a speed difference with respect to the moving speed of the photoconductor surface, thereby polishing and removing the toner remaining on the photoconductor surface layer together with the surface layer of the photoconductor. In the system cleaning device,
It is easy to damage the surface of the photoconductor or to vibrate the photoconductor during the polishing operation of the photoconductor surface layer of the cleaning roller. In addition, a charger is provided to recharge the surface of the photoconductor after passing through the transfer process, and this charger weakens the electrostatic attraction force between the residual toner on the photoconductor after passing through the transfer process and the surface of the photoconductor. After that, a method has been proposed in which residual toner is sent to the cleaning section to improve the mechanical cleaning effect in the cleaning section. As a result of mechanically removing the residual toner on the photoconductor in the cleaning section,
The surface of the photoconductor, which is the side to be trained, is always affected by the reaction of the mechanical toner removing force, and the vibration of the photoconductor is likely to occur.

The present invention has been made in view of the above background, and an object thereof is to obtain an average particle size distribution of 7
Clear toner and spherical toner of less than μm.
It is an object of the present invention to provide an image forming apparatus provided with a novel cleaning device capable of ensuring the margin of the training ability and reducing or preventing the vibration in the image forming system.

[0008]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention forms a latent image on a latent image carrier and develops the latent image by a developing device to form a toner. In the image forming apparatus, an image is formed, and after the toner image is transferred onto a transfer medium, the transfer residual toner remaining on the latent image carrier is removed by the cleaning device from the latent image carrier. A rotating body that is rotatably provided so as to come into contact with the surface of the latent image carrier and rotate with the movement of the surface; and a potential difference forming means that forms a predetermined potential difference between the rotating body and the latent image carrier. And a conductive roller portion made of an elastic material having a predetermined resistance on at least the surface portion of the rotating body, and an insulating elastic member positioned at both ends outside the conductive roller portion in the axial direction. Insulating roller made of material The one in which the features.

Here, the conductive roller portion of the rotating body is
For example, a rubber hardness of 15 ° to 70 ° (measured by an A-type hardness meter of JIS K6301) and a volume resistance of 10 6 to 10 16 around the center of the metal shaft in the longitudinal direction.
A conductive elastic layer (for example, a layer formed of conductive rubber) having a power of Ωcm is provided, and a volume resistance of 6 is provided on the rubber layer.
It can be formed by providing a roller-shaped member having a tube layer or coat layer made of a conductive fluororesin having a power of 10 to 16 16 Ωcm. The conductive roller portion can be used. And, the insulating roller portion,
For example, a rubber hardness of 1 is provided around both ends (outside of a roller portion in which the conductive elastic layer and the tube layer or coat layer are laminated) of the metal shaft portion of the rotating body in the longitudinal direction.
It can be formed by providing a layer made of an insulating rubber having an angle of 5 ° to 70 ° (measured by a JIS K6301 A type hardness meter).

The potential difference forming means forms a predetermined potential difference between the rotating body and the latent image carrier to form an electric field in a direction in which the toner moves from the surface of the latent image carrier to the surface side of the rotor. What can be formed is used. For example, a predetermined bias potential is applied to the rotating body, the rotating body is grounded directly or through a predetermined resistor, and the surface potential of the latent image carrier after the transfer process is reset to a predetermined potential. A charging unit for charging is installed upstream of the rotating body with respect to the moving direction of the latent image carrier. Any two or more of these may be combined and configured. It is desirable that the potential difference always occurs at least during the image forming operation. A resistance member having an extremely high resistance value can also be used as the resistor. Further, as the charging means, it is possible to use a charging means which applies an alternating current or a current obtained by superimposing an alternating current on a direct current.

An image forming apparatus according to a second aspect of the invention is characterized in that an annular groove is formed between the conductive roller portion and the conductive roller portion.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the width of the conductive roller portion in the axial direction is set to be equal to or larger than the toner image forming width on the latent image carrier. It is a feature.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the coefficient of static friction of the surface of the conductive roller portion with respect to the latent image bearing member is the latent image bearing of the surface of the insulating roller portion. Both roller parts are configured so that the coefficient of static friction with respect to the body is equal to or more than that.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, both roller portions are configured such that the diameter of the conductive roller portion is equal to or less than the diameter of the insulating roller portion. It is characterized by.

An image forming apparatus according to a sixth aspect of the present invention is the image forming apparatus according to the first aspect, wherein a cleaning member for removing adhered matters from the surface of the insulating roller portion is provided in contact with the surface. It is what

An image forming apparatus according to a seventh aspect of the present invention is the image forming apparatus according to the second aspect, wherein a cleaning member for removing adhering substances from the inner surface of the groove is provided in contact with the inner surface. Is.

[0017]

Embodiments Embodiments in which the present invention is applied to an electrophotographic copying machine which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a main part of a copying machine according to the embodiment. First, an outline of the entire copying machine will be described. In this copying machine, in FIG. 1, a main charger 2 uniformly feeds a rotating photosensitive drum 1 from a direction indicated by an arrow 3 through an original reading system and a writing system (not shown). A developing device 4 which forms an electrostatic latent image by exposure with the received original image light and uses polymerized toner (spherical toner produced by a polymerization method).
At, the toner is visualized as the electrostatic latent image. Next, the transfer charger 7 transfers the toner image on the photosensitive drum 1 onto the transfer paper 6 sent from the paper feed path 5 in synchronization with the rotation of the photosensitive drum 1. The transfer paper 6 on which the toner image has been transferred is separated from the surface of the photosensitive drum 1 by the separation charger 8. At this time, the transfer residual toner slightly left on the surface of the photoconductor is removed by the cleaning device 10 after the polarity and the charge amount are controlled by the charger 9 to a predetermined state. Then, the charge remaining on the photoconductor 1 after passing through the cleaning device 10 is discharged by the discharge lamp 11. On the other hand, the transfer paper 6 to which the toner image has been transferred and sent from the separation charger 8 is guided to the fixing device 13 by the transfer paper conveying device 12 and is heated and pressed to fix the toner image, The paper is discharged onto the paper discharge unit 14.

Next, the cleaning device 10 will be described in detail. In the image forming process, the residual toner on the photosensitive drum 1 that has passed through the charger 9 and is sent to the cleaning device 10 part passes through the inlet seal member 110 and reaches a part facing the elastic roller member 120. . Here, due to the electrostatic attraction force generated by the potential difference between the surface potential of the elastic roller member 120 due to the DC voltage applied to the core of the elastic roller member 120 and the surface potential of the photosensitive drum 1 after passing through the charger 9, The surface of the elastic roller member 120 is electrostatically captured.

This elastic roller member 120, as shown in FIG. 2, is a conductive roller-shaped portion 120 having an axial length L1.
a and the same shape portion 12a on both outer sides of the same shape portion 120a.
0a of the insulating roller-shaped portion 120b having a length L2 in the axial direction, which is provided with an annular groove portion of a predetermined width S from the end surface of the outer peripheral surface 0a. A predetermined DC voltage is applied by the power supply.

Of the roller-shaped portions 120a and 120b, the conductive roller-shaped portion 120a has a rubber hardness of 15 around the metal shaft portion as shown in the sectional structure of FIG.
° to 70 ° (measured by JIS K6301 A-type hardness tester) and volume resistance of 10 to 10 16 Ω
A tube made of a conductive fluorocarbon resin having a conductive elastic layer (for example, a layer formed of a conductive rubber) 121a of cm and a volume resistance of 10 to 10 16 Ωcm around the rubber layer. A layer or coat layer 122a is provided. On the other hand, the insulating roller shaped portion 120b is provided with the insulating elastic layer having the rubber hardness of 15 ° to 70 ° around the metal shaft portion.

The length L1 of the conductive roller shaped portion 120a in the axial direction is set to be equal to or longer than the maximum width W of the original image exposure on the photosensitive drum 1. This is because the residual toner can be reliably electrostatically captured on the surface of the conductive roller shape portion 120a even if the residual toner is widely sent in the axial direction of the conductive roller shape portion 120a or is sent in large quantities. Further, it is to ensure the accompanying rotation with respect to the surface of the photoconductor drum 1 by ensuring a surface portion that directly receives a mechanical gripping force and an electrostatic attraction force with the surface of the photoconductor drum 1. When the elastic roller-shaped member 120 is rotated with respect to the surface of the photosensitive drum 1, the insulating roller-shaped portions 120b provided on both sides of the conductive roller-shaped portion 120a are mechanically gripped with the surface of the photosensitive drum 1. You can contribute by receiving power. In order to ensure the rotation of the elastic roller member 120 more reliably, the coefficient of static friction of the peripheral surface of the insulating roller is equal to or more than the coefficient of static friction of the peripheral surface of the conductive roller 120a. It is desirable to set the outer diameter of the insulating roller shaped portion 120b to be equal to or larger than the outer diameter of the conductive roller shaped portion 120a.

When the residual toner from the surface of the photosensitive drum 1 enters the annular groove portion having the width S, the conductive roller shaped portion 120 is not provided with such a groove.
Unlike the case where a and the insulating roller-shaped portion 120b are arranged in close contact with each other, pressure is applied between the elastic roller member 120 and the surface of the photosensitive drum 1 to fix and cure them, thereby damaging the surface of the photosensitive drum 1. Is to prevent.

As described above, the elastic roller member 120 is
Is rotated by the rotation of the photoconductor drum 1 to be contacted, so that the photoconductor drum 1 is rotated by a mechanical force in the direction of rotation of the photoconductor drum 1 and is also assisted by the electrostatic attraction force. It will be. With the rotation of the elastic roller member 120, the elastic roller member 12 is moved from above the photosensitive drum 1.
The residual toner electrostatically captured on the peripheral surface of the conductive roller shaped portion 120a of No. 0 reaches the contact portion of the scraper blade member 130 made of sheet-shaped polyurethane held by the holding member 131, and by the scraper blade member 130, Peeled off from the surface of the elastic roller member 120,
The carrier coil 1 drops on the rotating carrier coil 150,
50 is discharged to the outside of the cleaning device.

Further, the residual toner adhered to the peripheral surface of the insulating roller 120b of the elastic roller member 120 for some reason has its tip end abutted on the peripheral surface, and the base end portion thereof has a cleaning device. The sheet-shaped mylar cleaning member 200 is fixed on the inner surface of the outer frame 10a in the vicinity of the transfer coil 150 by sticking with a double-sided adhesive tape or the like. As a result, the grip force between the insulating roller shaped portion 120b and the surface of the photosensitive drum 1 is stably exerted over time. The elastic roller member 12
The toner adhered to the inner surface of the annular groove of No. 0 is a cleaning made of a foamed urethane or rubber material whose base end is fixed by sticking with a double-sided adhesive tape in a posture in which the tip contacts the entire inner surface. It is removed by the pad member 201. As a result, it is possible to prevent scattering of the residual toner that has entered the annular groove portion and contamination of the surface of the tourist body due to reattachment of the residual toner on the surface of the photosensitive drum 1.

On the other hand, the residual toner remaining on the photosensitive drum 1 without being electrostatically captured by the elastic roller member 120 is removed from the sheet-shaped polyurethane rubber held by the holding member 161 by further rotation of the photosensitive drum 1. The cleaning blade member 160 reaches the contact portion, and is removed from the photosensitive drum 1 by the cleaning blade member 160. The peeled toner falls on the elastic roller member 120, and is discharged to the outside of the cleaning device through the same process as the above, together with the residual toner electrostatically captured on the elastic roller member 120.

[0026]

According to the image forming apparatus of the present invention, the residual toner remaining on the latent image carrier after passing through the transfer step and the surface of the latent image carrier after passing through the transfer process and the rotation contacting the surface are rotated. It is collected by electrostatic attraction due to the potential difference between the body and the conductive roller. Therefore, unlike a conventional cleaning device that performs cleaning by mechanical toner removing force using a fur brush or a cleaning roller having a latent image carrier surface polishing ability, the latent image carrier is vibrated or the latent image carrier surface is cleaned. It is possible to prevent it from being damaged. Further, since the conductive roller portion of the rotating body is in contact with and in close contact with the latent image carrier, the electrostatic attraction effect is continuously maintained and the residual toner is collected, so that the conventional toner is used. In addition to the above, a sufficient cleaning effect can be obtained not only for the toner having a smaller average particle diameter than the conventional one but also for the spherical toner. Further, since the insulating roller portions provided at both ends of the rotating body also come into contact with the latent image carrier and rotate, it is possible to prevent the generation of leakage current due to the insulating action of the insulating roller portion, and thus the conductive roller is provided. It is possible to stabilize the potential difference between the portion and the latent image carrier.

When the above-mentioned rotating body is brought into contact with the latent image bearing member and is rotated along with the mechanical force received from the surface of the latent image bearing member, the rotating operation of the contacting latent image bearing member is mechanically performed. In the direction of rotation of the latent image carrier by both the force (force of F = μN) that is generated by the contact force and the electrostatic attraction force generated by the potential difference between the surface of the latent image carrier and the surface of the rotor. Since it circulates around, it is not necessary to receive external driving for rotating the rotating body. Therefore, unlike a conventional cleaning device that rotationally drives a cleaning roller or the like by driving from the outside, vibration in the drive source or the drive transmission path from the drive source is
It is possible to prevent image unevenness called so-called banding due to transmission to the latent image carrier. Further, the insulating roller portion also comes into contact with the surface of the latent image bearing member and receives a mechanical force, so that it is possible to carry out the rotation more reliably.

In the image forming apparatus of the second aspect, since the annular groove portion is formed between the conductive roller portion and the insulating roller portion, the end portions of both roller portions contact each other. The toner collected from the surface of the latent image carrier by the conductive roller portion enters the minute gap between the contact portions of the end portions, receives pressure, and partially protrudes toward the surface side from the gap. Unlike the one that is fixedly accumulated, the solidified toner is less likely to be clumped between the roller portions. Therefore,
It is possible to prevent the latent image carrier surface from being damaged by such adhered toner.

In the image forming apparatus of the third aspect, since the width of the conductive roller portion in the axial direction is set to be equal to or larger than the toner image forming width on the latent image carrier, the transfer residual toner may occur. The conductive roller portion covers the entire certain width region, and such a transfer residual toner can be collected by the conductive roller portion. Moreover, since the insulating roller portion provided outside the conductive roller portion is also in contact with the surface of the latent image carrier, the residual toner enters the contact area of the conductive roller portion in a widely distributed state. The grip force is lost, and even if the rotating body of the rotating body is insufficient with only the mechanical rotating force due to the frictional force between the conductive roller unit and the latent image carrier, it is possible to reliably rotate. It can be performed. Therefore, it is possible to avoid a situation in which the rotating body can rotate only intermittently due to a lack of mechanical force received from the latent image carrier, and uneven collection of residual toner occurs.

In the image forming apparatus of the fourth aspect, the coefficient of static friction of the surface of the conductive roller portion with respect to the latent image carrier is equal to or more than the coefficient of static friction of the surface of the insulating roller portion with respect to the latent image carrier. As described above, since both the roller portions are configured, it is possible to obtain a larger entrainment force from the latent image carrier by the insulating roller portion. Therefore,
When selecting the material and surface structure of the conductive roller,
The restriction on the magnitude of the mechanical force received from the latent image carrier becomes relatively small, and the degree of freedom in selecting the material and surface structure can be increased.

In the image forming apparatus of the fifth aspect, since the diameter of the conductive roller portion is equal to or less than the diameter of the insulating roller portion, the latent image carrier for the rotating body to rotate with the latent image carrier. The mechanical force from is mainly applied to the insulating roller portion. Unlike the conductive roller portion, the insulating roller portion rarely changes the mechanical force received from the latent image carrier due to the change in the amount of residual toner,
Stable mechanical force can be received. Therefore, the mechanical force for rotating the rotating body as a whole from the latent image carrier is stabilized, and the rotating body can be rotated stably.

In the image forming apparatus according to the sixth aspect of the present invention, the cleaning member removes the adhering substances from the surface of the insulating roller portion, so that toner adhesion can be prevented from occurring on the surface, and the insulating roller portion is hidden. It is possible to stabilize the mechanical force for the accompanying rotation received from the image carrier. Therefore, the rotation of the entire rotating body with respect to the latent image carrier can be stabilized over time.

In the image forming apparatus according to the seventh aspect, since the cleaning member provided in contact with the inner surface of the groove portion according to the second aspect removes the deposits from the inner surface, the conductive roller portion and the insulating roller portion are removed. It is possible to more effectively prevent damage to the surface of the latent image carrier due to the occurrence of solidified toner particles between the toner and the toner, and also to prevent toner scattering.

[Brief description of drawings]

FIG. 1 is a front view showing a schematic configuration of an electrophotographic copying machine according to an embodiment.

FIG. 2 is a partial perspective view of a cleaning device of the copying machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum 4 Developing device 6 Transfer paper 7 Transfer charger 8 Separation charger 9 Charging device 10 Cleaning device 10a Cleaning device outer frame component member 11 Static elimination lamp 12 Transfer paper transport device 13 Fixing device 110 Inlet system -Member 120 elastic roller member 120a conductive roller shape portion 120b insulating roller shape portion 121a conductive rubber layer (elastic layer) 122a conductive fluororesin layer (tube layer or
(Coat layer) 130 Scraper blade member 131 Holding member 150 Conveying coil 160 Cleaning blade member 200 Sheet-shaped mylar cleaning member 201 Cleaning pad member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Okamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Kenzen Sekine 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Inventor Yasunori Kawaishi 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd.

Claims (7)

[Claims] 1. A latent image is formed on a latent image carrier, the latent image is developed by a developing device to form a toner image, and the toner image is transferred onto a transfer medium. In an image forming apparatus for removing the transfer residual toner remaining on the latent image carrier from the latent image carrier, the cleaning device is rotatable so as to come into contact with the surface of the latent image carrier and move along with the movement of the surface. And an electric potential difference forming means for forming a predetermined electric potential difference between the rotating body and the latent image carrier. An image forming apparatus comprising: a conductive roller portion made of a material; and an insulating roller portion made of an insulating elastic material located at both ends outside the conductive roller portion in the axial direction. 2. The image forming apparatus according to claim 1, wherein an annular groove is formed between the conductive roller portion and the conductive roller portion. 3. The image forming apparatus according to claim 1, wherein the width of the conductive roller portion in the axial direction is set to be not less than the toner image forming width on the latent image carrier. 4. The image forming apparatus according to claim 1, wherein the coefficient of static friction of the surface of the conductive roller portion with respect to the latent image carrier is equal to or more than the coefficient of static friction of the surface of the insulating roller portion with respect to the latent image carrier. An image forming apparatus characterized by comprising both roller parts. 5. The image forming apparatus according to claim 1, wherein both roller portions are configured such that a diameter of the conductive roller portion is equal to or smaller than a diameter of the insulating roller portion. . 6. The image forming apparatus according to claim 1, wherein a cleaning member for removing adhered substances from the surface of the insulating roller portion is provided in contact with the surface. 7. The image forming apparatus according to claim 2, wherein a cleaning member for removing adhered substances from the inner surface of the groove is provided in contact with the inner surface.