JP2002139973A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that suppresses degradation of image quality by suppressing wear of an absorbing member due to contact with a body to be electrified. SOLUTION: The device has a corona discharger 20 that electrifies a photoreceptor drum 10, which is to be electrified, by means of discharge, and an absorbing roller 80 that is in contact with the surface of the photoreceptor drum 10 and absorbs discharge products produced by the discharge. The device is also provided with a contact/separation means (not shown) that is used for the absorption roller 80 so as to selectively bring the absorption roller 80 into contact with the photoreceptor drum 10 and separates the roller 80 therefrom.

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.
The present invention relates to an image forming apparatus including a charging unit that charges a charging target by discharging.

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus, before forming an electrostatic latent image on a photoconductor as an image carrier, the surface of the photoconductor is uniformly charged by various methods. As a charging method for charging the photoreceptor, a non-contact charging method in which a corona discharge is generated and charged without contacting the image carrier, or a method in which a voltage is applied to a contact charging member such as a charging roller or a charging brush, is used. There is a contact charging system in which charges are directly injected into an image carrier.
In the non-contact charging method, discharge products such as nitrogen oxides are generated during the discharge. In the contact charging method,
When a bias is applied to the contact charging member, discharge occurs on both sides of the portion where the contact charging member contacts the photoconductor. For this reason, in the contact charging method, a discharge generating substance is similarly generated.

[0003] Nitrogen oxide, which is a discharge generating substance, reacts with moisture in the air or the like to generate nitric acid, and reacts with metal to generate metal nitrate. When the nitric acid or nitrate generated as described above adheres to the surface of the photoreceptor to form a thin film, the resistance of the surface of the photoreceptor decreases due to the hygroscopic action of the nitric acid or nitrate. As a result, there is a problem that the electrostatic latent image formed on the photoconductor is destroyed and the quality of the formed image is reduced.

FIG. 11 shows the photoreceptor surface potential when the discharge product does not adhere to the photoreceptor surface (a) and when the discharge product adheres to the photoreceptor surface (b). As shown in FIG. 11A, when the discharge product is not attached, the charge is uniformly charged by the charging unit and the potential thereof becomes the charging potential VD. It becomes the exposure potential VL. On the other hand, as shown in FIG. 11B, when a discharge product is adhered to the surface of the photoconductor, FIG.
As a result of exposing an area equal to 1 (a), the surface of the photoreceptor in the exposed area does not reach the exposure potential VL, but changes only to VL 'close to the charging potential. This is because the discharge products adhering to the photoreceptor surface and absorbing moisture reduce the resistance of the discharge product attachment portion on the photoreceptor surface, and the charge generated by exposure spreads over the photoreceptor surface beyond the exposure area to the periphery. This is because As a result, the potential of the exposure area does not sufficiently fall, and the potential outside the exposure area slightly decreases,
A sharp and deep latent image is not formed, and toner is not sufficiently adhered to the image portion even when the image is developed, so that an abnormal image such as flowing image is generated. In particular, in a high-humidity environment, such an abnormal image is likely to occur because the discharge-producing substance easily absorbs moisture.

Conventionally, the surface of the photoreceptor is mechanically cleaned by a cleaning member such as a blade or a brush which constitutes a cleaning means for recovering the transfer residual toner remaining on the photoreceptor. It was rubbed and scraped off. As a result, the occurrence of an abnormal image due to the discharge-producing substance could be suppressed to some extent. However, when the cleaning member removes the discharge generating material on the surface of the photoreceptor, the surface of the photoreceptor is also removed together with the discharge generating material, which causes a problem that the life of the photoreceptor is reduced.

On the other hand, as cleaning means for cleaning the transfer residual toner remaining on the photoreceptor, a cleaning carrier (magnetic brush) held by a cleaning roller having a built-in magnet is brought into contact with the transfer residual toner, and a bias is applied. There has been proposed a magnetic brush cleaning system in which residual toner is adsorbed to a cleaning carrier by an electric field (see, for example, Japanese Patent Application Laid-Open No. H5-111964). In addition, a cleaner-less method has been proposed in which a transfer device is not used, and the transfer residual toner remaining on the photoreceptor is recovered using a developing device or the like (for example, Japanese Patent Application Laid-Open No.
-30898). In the magnetic brush cleaning method and the cleanerless method, since the surface of the photoconductor is not shaved by the cleaning member, the life of the photoconductor can be extended while maintaining high image quality.

Further, in order to make the surface of the photosensitive member less likely to be scraped by the cleaning member, it is conceivable that the surface of the photosensitive member is made of a material having high hardness such as amorphous silicon.

However, in the image forming apparatus to which the magnetic brush cleaning method and the cleanerless method are applied, there is no cleaning member which has also a function of scraping a nitric acid or nitrate film conventionally. When the surface of the photoreceptor is made of a material having high hardness, the surface of the photoreceptor is hard to be scraped, so that the surface of the photoreceptor may enter into the unevenness or adhere to the surface by a chemical reaction with the surface of the photoreceptor. Nitric acid or nitrate cannot be removed. Therefore,
There is a need to remove such discharge-generating substances by other methods.

Japanese Patent Application Laid-Open No. Sho 60-49352 discloses an image forming apparatus capable of removing a nitric acid or nitrate film on a photoreceptor without shaving the surface of the photoreceptor. This image forming apparatus is provided with a water cleaning means for cleaning the surface of the photoreceptor with water, and removes water-soluble nitric acid or nitrate by the water cleaning means.

[0010]

However, in the image forming apparatus described in JP-A-60-49352,
As the water cleaning means, two rollers, a water application roller for applying water to the surface of the photoreceptor and a removal roller for removing nitric acid or nitrate dissolved in the applied water together with water, are used, and a space for disposing them is used. Is required around the photoreceptor. For this reason, the entire image forming apparatus becomes large,
There is a problem that this is contrary to the miniaturization of the device.

Therefore, the present applicant has previously filed Japanese Patent Application No.
Japanese Patent No. 14217 proposes an image forming apparatus which has a simple configuration and removes a discharge-generating substance generated by electric discharge, thereby improving image quality, extending the life of an image carrier, and miniaturizing the entire apparatus. did. This image forming apparatus is provided with a discharge-product adsorbing / removing unit having a simple configuration for adsorbing and removing a discharge-generated substance generated by discharge.

FIG. 12 shows an example of the construction of the means for removing and adsorbing discharge-producing substances to which the technique proposed in Japanese Patent Application No. 12-314217 is applied. In the illustrated example, the photosensitive member 1 as an image bearing member is used as a discharge generating substance adsorption removing unit.
In this embodiment, an adsorbing member 80 is used that adsorbs a discharge product by contacting with a zero. The adsorbing member 80 is a rotatable roller-shaped member composed of a surface layer 81 made of a water-absorbing material and a lower layer 82 made of an elastic body and a water-containing material. Further, the lower layer 82 is impregnated with moisture as an adsorbent, so that moisture is supplied from the lower layer 82 to the surface layer 81. In the above configuration, when the photoreceptor 10 and the adsorbing member 70 rotate in the co-rotating direction while being in contact with each other, the water supplied from the lower layer 82 to the surface layer 81 by the contact rotation rotates the surface layer 8.
1 oozes on the surface. The exuded water is supplied to the surface of the photoconductor upstream of the entrance of the contact nip in the moving direction of the surface of the photoconductor, and is supplied to the discharge generating material on the surface of the photoconductor 10. Further, moisture is supplied to the discharge generating material on the surface of the photoreceptor even in the contact nip portion. A part of the discharge generating material supplied with water in this way dissolves in the water, and the other part becomes wet, so that the adhesion to the photoreceptor 10 is reduced. The discharge-generating substance dissolved in the water or having reduced adhesion to the photoreceptor 10 is adsorbed on the surface layer 81 by being pressed in the contact nip portion, or the adsorption roller 80 is brought into contact with the photoreceptor 10. In the vicinity of the outlet of the contact nip portion opened from the surface, the surface layer 81 made of a water-absorbing material absorbs the moisture together with the moisture and is removed from the surface of the photoreceptor 10. As described above, since the discharge-producing substance can be removed by using the adsorption member 80 having the simple configuration including the surface layer 81 and the lower layer 82, the image forming apparatus described in JP-A-60-49352 can be removed. It is possible to reduce the size of the entire device.

However, the above-mentioned Japanese Patent Application No. 12-3142 is disclosed.
Also in the image forming apparatus of No. 17, if the image carrier and the adsorbing member are always kept in contact with each other, for example, the abrasion due to the contact of the adsorbing member is promoted, and the ability to adsorb and remove the discharge-producing substance is reduced. The fear remained. As described above, when the adsorbing and removing ability of the adsorbing member is reduced, a problem that image quality is deteriorated occurs.

The present invention relates to the above-mentioned Japanese Patent Application No. 12-314217.
The purpose of the present invention is to reduce the wear of the suction member due to the contact with the charged object,
An object of the present invention is to provide an image forming apparatus capable of suppressing a decrease in image quality.

[0015]

According to a first aspect of the present invention, there is provided an image forming apparatus provided with a charging means for charging an object to be charged by discharging, the image forming apparatus comprising: A state in which the discharge member includes a discharge-producing substance adsorption removing unit configured to adsorb a discharge generation substance generated by the discharge, and the adsorption member contacts an object to be charged.
It is characterized in that a contacting / separating means for the adsorbing member is provided so as to selectively take a state of being separated from the charging target.

In this image forming apparatus, the adsorbing member is brought into contact with the charging object only when necessary by the contact / separation means,
By preventing the contact, the wear of the adsorption member due to the contact can be suppressed while exhibiting the ability to adsorb and remove the discharge-producing substance.

According to a second aspect of the present invention, there is provided the image forming apparatus of the first aspect, wherein the control unit controls the contact / separation means so that the suction member is separated from the charging target during the image forming operation. A means is provided.

In this image forming apparatus, during the image formation, the suction member is kept away from the charging object, so that the chance of scattering toner during development and transfer and toner remaining after cleaning adhere to the suction member is reduced. And the contamination of the adsorption member can be suppressed.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the control means is configured to perform the operation of bringing the adsorbing member into and out of operation so as to adsorb the discharge generating material every time a series of image forming operations is completed. The contact / separation means is controlled so as to perform the following. Here, the end of a series of image forming operations is, for example, each end of a continuous copying operation when the image forming apparatus is a copying machine, and a personal computer when the image forming apparatus is a printer. At the end of continuous output based on the image information from.

In this image forming apparatus, every time a series of image forming operations is completed, the adsorbing member is brought into contact with the charging target to adsorb and remove the discharge-generating substance to some extent, thereby efficiently removing the discharge-generating substance. It can be carried out.
Further, it is advantageous in that wear of the suction member is suppressed.

According to a fourth aspect of the present invention, in the image forming apparatus of the second aspect, the control means moves the adsorbing member so as to adsorb the discharge generating material prior to starting a series of image forming operations. The contact / separation means is controlled so as to perform the following. Here, each time a series of image forming operations is started is, for example, when the image forming apparatus is a copying machine, each time a continuous copying operation is once completed, and then each time a next copying operation is started. In the case of a printer, it is each time the next output is started after continuous output based on image information from a personal computer or the like is once ended.

In this image forming apparatus, prior to the start of a series of image forming operations, the adsorbing member is brought into contact with the object to be charged to remove the discharge-generating substance from the surface of the object to be charged. It is possible to reliably remove the generated discharge-producing substance on the surface to be charged before forming an image. Further, it is advantageous in that wear of the suction member is suppressed.

According to a fifth aspect of the present invention, in the image forming apparatus of the first aspect, the charging target is an image carrier for carrying an electrostatic latent image or a visible image, and the image forming operation is continuously performed. When the surface between the rear end of the preceding image forming area and the front end of the succeeding image forming area on the surface of the image carrier faces the adsorbing member, to adsorb the discharge generating material,
Control means for controlling the contact / separation means is provided to perform the contact / separation operation of the suction member.

In this image forming apparatus, when performing an image forming operation continuously, the front end of the preceding image forming area and the front end of the succeeding image forming area on the surface of the image carrier to be charged. When the surface in between faces the adsorbing member, the adsorbing member is brought into contact with the image carrier to adsorb and remove the discharge generating material, thereby relatively increasing the number of times the discharge generating material is removed. The material can be removed before it has settled on the image carrier. Therefore, it is possible to more reliably remove the discharge generating material.

According to a sixth aspect of the present invention, in the image forming apparatus of the first aspect, the charging target is a transfer material transporting member for carrying and transporting the transfer material, and when the image forming operation is continuously performed, When a surface between the rear end of the preceding transfer material and the front end of the succeeding transfer material among the surfaces of the transfer material transport member faces the suction member, the suction member is used to perform suction of the discharge generating substance. A control means for controlling the contact / separation means is provided so as to perform the contact / separation operation.

In this image forming apparatus, when the image forming operation is continuously performed, a portion between the rear end of the preceding transfer material and the front end of the subsequent transfer material on the surface of the transfer material conveying member to be charged is used. When the surface of the first member faces the adsorbing member, the adsorbing member is brought into contact with the transfer material conveying member to adsorb and remove the discharge generating material, so that the discharge generating material is transferred in the same manner as described in claim 5. It becomes possible to remove it before it is fixed on the material conveying member. Therefore, it is possible to more reliably remove the discharge generating material.

According to a seventh aspect of the present invention, in the image forming apparatus of the first aspect, the image forming apparatus further includes a driving unit for rotating the charging target, and performs the adsorption of the discharge generating material during an initial operation after the power is turned on. A control means for controlling the driving means and the contact / separation means is provided so as to rotate the charging object and bring the suction member into contact with the charging object.

In this image forming apparatus, during the initial operation after the power is turned on, the charging target is rotated and the adsorption member is brought into contact with the charging target to remove the discharge-generating substance from the surface of the charging target. During this time, the discharge-producing substance on the surface of the charging target fixed by strong adhesive force can be removed. Further, it is advantageous in that wear of the suction member is suppressed.

The invention according to claim 8 is based on claims 1, 2, 3,
4, 5, 6, or 7, wherein the charging target is a rotatable rotating body, and a contact time between the suction member and the charging target is one or more rotations of the charging target. It is assumed that.

In this image forming apparatus, the adsorbing member is brought into contact with the object to be charged for at least one rotation of the object to be adsorbed to remove the discharge-generating substance. Substances can be removed.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter simply referred to as "copier") as an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram illustrating a main part of a copying machine according to the present embodiment. This copying machine performs single-color copying, and forms a monochrome image based on image data read by an image reading unit (not shown).

First, the configuration of the entire copying machine according to the present embodiment will be described. In FIG. 1, the copying machine includes a drum-shaped photoconductor 1 as an image carrier. Photoconductor 10
Around, a corona discharger 20 as charging means, an optical writing unit 30 as latent image forming means for forming a latent image on the photoreceptor 10, and a developing device 40 as developing means for developing the latent image into a toner image A transfer roller 50 for transferring a toner image formed by the developing device 40 onto a transfer sheet P as a transfer-receiving member, and a cleaning unit for cleaning toner remaining on the surface of the photoreceptor 10 after the transfer. A unit 60, a static elimination lamp 70 for neutralizing the surface of the photoconductor 10, and the like are arranged.

A roller around the photoreceptor 10 serving as a discharge-producing substance adsorbing and removing means for adsorbing and removing the discharge-producing substance generated by the corona discharger 20 in contact with the surface of the photoreceptor 10. A suction member (hereinafter, referred to as a suction roller) 80 is also provided. The configuration of the suction roller 80 will be described later in detail.

The corona discharger 20 includes the photosensitive drum 1
The photoconductor drum 10 is disposed in a non-contact manner at a predetermined distance from the surface of the photosensitive drum 10 to apply a voltage to a discharge wire to charge the photosensitive drum 10 to a predetermined polarity and a predetermined potential by corona discharge. In the present embodiment, the photosensitive drum 10 is uniformly charged to a negative polarity.

The optical writing unit 30 uses an LD as a light emitting element and irradiates a laser beam to the photoconductor 10 based on image data to form an electrostatic latent image. In this embodiment, an LD is used as a light emitting element, but an LED or the like may be used.

The developing device 40 has a developing roller 41 as a developer carrying member which contains a magnet as a magnetic field generating means. A developing bias is applied to the developing roller 41 from a power source (not shown). Two agitating screws 42 and 43 are provided in the casing of the developing device 40 to agitate while transporting the two-component developer containing the toner and the carrier contained in the casing in opposite directions. Further, a doctor blade 44 for regulating the developer carried on the developing roller 41 is also provided. The toner in the developer stirred and conveyed by the two stirring screws is charged to a negative polarity. Then, the developer is pumped up by the developing roller 41 by the action of the magnet included in the developing roller 41. The pumped-up developer is regulated by the doctor blade 44, and in the developing area facing the photoreceptor drum 10, is brought into a standing state by a magnetic force of a magnet to form a magnetic brush.

The cleaning unit 60 includes a blade-shaped cleaning member (hereinafter, referred to as a cleaning blade) 61 that rubs the surface of the photoconductor 10.
Further, a toner discharge screw 62 for collecting the toner cleaned by the cleaning blade 61 and discharging the toner to the outside of the casing of the cleaning unit 60 is provided.

A transfer bias is applied to the transfer roller 50 from a power source (not shown).

Next, an image forming operation (copy operation) in the copying machine having the above configuration will be described. In the above configuration, when the copy start button of the operation unit (not shown) is pressed,
The reading of the document is started by an image reading unit (not shown), and the corona discharger 20, the developing roller 41,
A predetermined voltage or current is sequentially applied to the transfer roller 50 at a predetermined timing. Further, in synchronization with this, the photoconductor 10 is rotationally driven in the direction of arrow A in the figure by a photoconductor driving motor (not shown) as a driving unit. Further, simultaneously with the rotation driving of the photoconductor 10, the developing roller 41,
The transfer roller 50, the stirring screws 42 and 43, and the toner discharge screw 62 are also driven to rotate in a predetermined direction. At this time, the suction roller 80 is stopped in a state of being separated from the photoconductor 10 as described later in detail.

When the photoreceptor 10 rotates in the direction of arrow A in the figure, first, the surface of the photoreceptor is charged to a potential of, for example, -900 V by the corona discharger 20. Then, a laser beam corresponding to the image signal is transmitted from the optical writing unit 12 to the photoconductor 1.
The potential on the photoconductor drum 10 at the portion irradiated with the laser beam on the photoconductor drum 10 is reduced to, for example, -150 V, and an electrostatic latent image is formed.

The photoreceptor 10 on which the electrostatic latent image is formed is rubbed on the surface of the photoreceptor drum 10 by the ears of the developer formed on the developing roller 41 at a portion facing the developing device 40. At this time, the negatively charged toner on the developing roller 41
Due to a developing bias of, for example, -600 V applied to the image No. 1, the toner image moves to the electrostatic latent image side and is formed into a toner image (developed).
As described above, in the present embodiment, the electrostatic latent image formed on the photoreceptor 10 is reversely developed by the developing device 40 using the negatively charged toner.

The toner image formed on the photoreceptor 10 is transferred from a paper supply unit 100 via registration rollers 91 and 92 to a transfer area formed between the photoreceptor 10 and the transfer roller 50. It is transferred to paper P. During this transfer, a transfer bias controlled at a constant current of, for example, +10 μA is applied to the transfer roller 50. The transfer paper P on which the toner image has been transferred is transferred to the photosensitive member 1 by a separation claw 93 serving as separation means.
The toner image is separated from the toner image and is conveyed to a fixing device 110 as a fixing unit. Then, the toner image is fixed on the transfer paper P by the action of heat and pressure by passing through a nip between the heating roller 111 and the pressure roller 112 of the fixing device 110, and is discharged outside the apparatus.

On the other hand, on the surface of the photoreceptor 10 after the transfer, the residual toner after the transfer is removed by the cleaning blade 61, and the charge is further removed by the discharge lamp 70.

Next, a description will be given of the suction roller 80 as the discharge-product-sucking and removing means, which is a feature of the present embodiment. FIG. 2 is a sectional view of the suction roller 80 in the axial direction. As shown, the suction roller 8 of the present embodiment is
0 is a surface layer 81 made of a highly water-absorbing material, a lower layer 82 made of a foam or a porous body that is an elastic and water-containing material,
And a hollow core shaft 83. The suction roller 80 is rotatably supported by a bearing 153 attached to a pre-oscillation frame 152 and an after-oscillation frame 150 shown in FIG. 3 described later, and rotates together with the photoconductor 10. I have. Further, the lower layer 82 is impregnated with moisture as an adsorbent, so that moisture is supplied from the lower layer 82 to the surface layer 81. Then, the surface layer 82 to which the water has been supplied becomes gel-like, has an adhesive property, and keeps an appropriate amount of water. The water may be a fluid, a mist, or a vapor gas. Further, as disclosed in Japanese Patent Application No. 12-314217, the hollow core shaft 83 of the suction roller 80 is provided.
In addition to connecting a water tank as a water replenishing means, a plurality of water replenishing openings are provided in the core shaft 83, and the water from the replenishing tank may be appropriately supplied to the lower layer 82 via the replenishing openings. Good.

In the above configuration, as shown in FIG. 1, when the photosensitive member 10 comes into contact with the suction member 80 and the suction roller 80 rotates in the direction of the arrow in FIG.
Due to the contact rotation, the moisture supplied and retained from the lower layer 82 to the surface layer 81 oozes out on the surface of the surface layer 81. The exuded water is supplied to the surface of the photoconductor upstream of the entrance of the contact nip in the moving direction of the surface of the photoconductor, and
It is supplied to the surface discharge products. Further, moisture is supplied to the discharge generating material on the surface of the photoreceptor even in the contact nip portion. The discharge-generating substance supplied with water in this way is:
Part of it dissolves in the water and the other part becomes moist, and the adhesion to the photoreceptor 10 decreases. The discharge-generating substance dissolved in the water or having a reduced adhesion to the photoconductor 10 is adsorbed on the surface layer 81 by being pressed in the contact nip portion, or is adsorbed on the adsorption roller 8.
Numeral 0 is near the exit of the contact nip portion that is released from contact with the photoreceptor 10 and is absorbed by the surface layer 81 made of a water-absorbing material together with the water and removed from the surface of the photoreceptor 10.

The discharge-producing substance absorbed by the surface layer 81 and held inside the surface layer 81 may be partially exuded again with moisture when the suction roller 80 rotates once. However, since the discharge-producing substance that is nitric acid or nitrate can be dissolved in water in a large amount, even if it exudes with water, it is taken into the surface layer 81 again together with the next discharge product. Therefore, the suction roller 8
No discharge product remains on the surface of the photoreceptor 10 that has passed through the contact nip portion with zero.

In the above-described structure, since the discharge-generating substance can be removed by using the adsorption member 80 having a simple structure including the surface layer 81 and the lower layer 82, the structure described in Japanese Patent Application Laid-Open No.
It is possible to reduce the size of the entire apparatus as compared with the image forming apparatus described in JP-A-49352.

In the present embodiment, the suction roller 80 can selectively take a state in which the suction roller 80 is in contact with the photoconductor 10 and a state in which the suction roller 80 is separated from the photoconductor 1.
The contact / separation mechanism as the contact / separation means is provided. FIG. 3 is a schematic configuration diagram illustrating a contact / separation mechanism of the suction roller 80 according to the present embodiment. Both ends of the hollow core shaft 83 of the suction roller 80 are rotatably supported by the pre-oscillation frame 152 and the post-oscillation frame 150 via bearings 153a and 153b.
The pressing force of the bearing 153 is adjusted by pressing springs 154a and 154b so that the pressing force against the photoconductor 10 is kept constant. The pre-oscillation frame 152 and the post-oscillation frame 150 are connected to the supporting side plate 200 of the copying machine main body.
It is fixed to a swing center shaft 151 rotatably supported by a and b, and is configured to be swingable about the swing center shaft 151. Then, the supporting side plate 200 of the swing center shaft 151
The solenoid 1 is connected to the end on the b side through a rotation pin 147.
The arm 149 that transmits the movement of the link 45 and the link 146 to the swing center shaft 151 is fixed. Link 14
6 is rotatably attached to the solenoid 145 by a swing pin 148.

In the above configuration, the solenoid 145 is
When N, the link 146 moves in the arrow B direction. With this movement, the swing center shaft 151 rotates together with the arm 149 by a predetermined angle in the direction of arrow C in the figure, and the pre-swing frame 152 and the post-swing frame 150 swing according to the rotation angles. Thereby, the suction roller 80 is also moved to the swing center shaft 151.
, And comes into contact with the photoconductor 10 as shown in FIG. Further, the suction roller 80 is moved to the photosensitive member 1.
When separating from zero, the current of the solenoid 145 is released, and the separation spring 150 fixed to the main body side plate (not shown) pulls the arm 149 in the direction of arrow D in the figure. As a result, the suction roller 80 rotates in the direction of arrow E in the figure around the swing center shaft 151, and the suction roller 80 is separated from the photoconductor 10 as shown in FIG.

By using the contact / separation mechanism as described above, the suction roller 80 is brought into contact with the photoreceptor 10 only when necessary, and is kept out of contact with the photoreceptor 10. The abrasion of the suction roller 80 due to this can be suppressed. As a result, it is possible to suppress a decrease in image quality over a long period of time. Further, the life of the suction roller 80 can be extended.

Next, the execution timing control of the contact / separation operation of the contact / separation mechanism having the above configuration will be described. In the present embodiment, during the image forming operation, the contact / separation operation is controlled by a control unit (not shown) as control means such that the suction roller 80 is separated from the photoconductor 10. In the copying machine of the present embodiment, a main control unit (not shown) has a function as a control unit of a contact / separation mechanism, and a photoconductor drive motor for rotating and driving the photoconductor 10, a corona discharger 20, a developing bias power supply, It also controls the bias power supply and the like.

FIG. 5 is a flowchart showing an example of the execution timing control. In the example of FIG. 5, the control is performed such that the suction roller 80 is brought into contact with and separated from the discharge roller in order to perform the suction removal of the discharge-generated substance every time a series of image forming operations is completed, that is, each time a continuous copy operation is completed. I do. First, it is determined whether or not a series of image forming operations is completed (S1). When the image forming operations are completed, another image forming operation end routine is executed while the photoconductor 10 is continuously driven to rotate (step S1). S2). The image forming operation end routine is a control routine for turning off the corona discharger 20, the developing bias power supply and the transfer bias power supply, and stopping the rotation of the developing roller 41 and the transfer roller 50. Next, when it is detected by a sensor (not shown) that the rear end of the toner image forming area on the photoreceptor surface after the transfer has passed the area facing the suction roller 80 (S
3), the solenoid 145 of the contact / separation mechanism is turned on, the suction roller 80 is brought into contact with the photoconductor 10, and the timer (not shown) starts counting (S4). With the start of the timer, the operation of adsorbing and removing the discharge-producing substance on the surface of the photoconductor 10 is started. The set time of the timer, that is, the contact time between the attraction roller 80 and the photoreceptor 10 is set to a time of one rotation or more of the photoreceptor 10 in order to remove the discharge-generating material over the entire surface of the circumference of the photoreceptor 10. desirable.
If a timeout has occurred (Yes in S5), it is determined that the operation of adsorbing and removing the discharge-producing substance has been completed, and the solenoid is turned off to separate the attraction roller 80 from the photoconductor 10, and the drive motor of the photoconductor 10 is driven. OFF
(S6), and ends the control.

According to the example of the control of the timing of execution of the contact / separation operation, since the discharge-producing substances are collectively adsorbed and removed to some extent, the discharge-producing substances can be efficiently removed.
Further, it is advantageous in that wear of the suction roller 80 is suppressed.

In the control example shown in FIG. 5, each time the series of image forming operations is completed, the contact / separation operation of the attraction roller 80 is performed. However, the discharge is performed prior to the start of the series of image forming operations. Control may be performed such that the suction roller 80 is brought into and out of contact in order to perform adsorption of the generated substance. Specifically, after the copy start button of the operation unit (not shown) is pressed,
The drive motor of the photoconductor 10 is turned on, and the solenoid 145 is turned on, so that the suction roller 80 that has been separated from the photoconductor 10 is brought into contact with the photoconductor 10. Then, after the operation of adsorbing and removing the discharge-producing substance is completed, the solenoid is turned off to separate the attraction roller 80 from the photoconductor 10, and then the copying operation is started. According to this, the discharge-producing substance on the surface of the photoreceptor 10 adhered with a strong adhesive force when left unattended can be reliably removed before image formation.

In the case where the control section continuously performs the image forming operation, the surface between the rear end of the preceding toner image forming area and the front end of the succeeding toner image forming area on the surface of the photoconductor 10. That is, when the surface of the photoreceptor 10 corresponding to the "sheet interval" faces the suction roller 80, the suction roller 80 is brought into contact with and separated from the suction roller 80 so as to remove the discharge generation material in order to adsorb the discharge generation material. Is also good. Specifically, when a sensor (not shown) detects that the rear end of the first toner image forming area on the surface of the photoconductor 10 has passed the area facing the suction roller 80, the solenoid 145 of the contact / separation mechanism is turned on.
N, the suction roller 80 is brought into contact with the photoconductor 10. Then, after the operation of adsorbing and removing the discharge generating material is completed, the solenoid is turned off to separate the attraction roller 80 from the photoconductor 10, and then the image forming operation of the second sheet is started. This is repeated for the number of copies. According to this, since the discharge generating material is removed for each sheet, it is possible to remove the discharge generating material before the discharge generating material is fixed to the surface of the photoreceptor 10, and it is possible to more reliably remove the discharge generating material.

Further, at the time of the initial operation after the power is turned on, the above-mentioned control unit controls the photosensitive member 10 so as to adsorb the discharge-producing substance.
The drive motor of the photoreceptor and the solenoid 145 of the contact / separation mechanism may be controlled so as to rotate the suction roller 80 and the photoreceptor 10. Specifically, after the main switch (not shown) is pressed, the drive motor of the photoconductor 10 is turned on while the heating roller 111 of the fixing device 110 is heated to a predetermined temperature by a built-in heater, for example. When the solenoid 145 is turned on, the suction roller 80 separated from the photoconductor 10 is brought into contact with the photoconductor 10. At the same time as the end of the initial operation, the solenoid is turned off and the suction roller 80 is moved to the photosensitive member 1.
At the same time, the drive motor of the photoconductor 10 is turned off. According to this, it is possible to remove the discharge generating substance on the surface of the photoreceptor 10 which is fixed with a strong adhesive force while the power is turned off.

The superabsorbent material constituting the surface layer 81 includes polyalkyl oxides such as polyethylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl butyral, polyacrylamide, polypropylene glycol, glue, gelatin, casein, albumin, and alginic acid. , Sodium alginate, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl ether, polyvinylmethylcellulose, polyethylene glycol, glucose, xylose, sucrose, maltose, arabinose, α-cyclodextrin, copolymers such as starch,
A graft polymer, a crosslinked product, or the like can be used.
However, it is not limited to these.

Further, examples of the highly water-absorbing member of the surface layer 81 include polyacrylic acid, polymaleic acid, polymethacrylic acid, polyacrylamide, and polyacrylic acid soda, and their derivatives and copolymers thereof. Polymers and the like.

As the water-containing material which is an elastic body constituting the lower layer 81, urethane rubber, silicon rubber,
A foam such as ethylene propylene rubber, butadiene rubber, styrene rubber, chloroprene rubber, butylene rubber, or an elastomer, or a porous body such as sponge or urethane foam can be used. However, it is not limited to these.

In the above embodiment, the corona discharger 20 is used as the charging means for the photoconductor, and the cleaning blade 61 is used as the cleaning means for the photoconductor. However, the present invention is not limited to these. For example, as a charging unit, a charging roller 21 of a contact charging system as shown in FIG. 6 can be applied. Further, as the cleaning means, a magnetic brush cleaning method using a brush member 63 as shown in FIG. 7 or a cleaning roller 64 having a built-in magnetism as shown in FIG. 8 is also applicable. Note that the brush-like member 66 in FIG. 7 is a seal brush for preventing the developer in the cleaning device 60 from leaking. Further, various combinations are possible, such as using the charging roller 21 and the brush member 63 as shown in FIG. 9, or using the charging roller 21 and the cleaning roller 64 of the magnetic brush cleaning type as shown in FIG. .

In the above embodiment, the case where the charging object is the photosensitive member as the image carrier has been described. However, the present invention is applicable to the case where the charging object is the intermediate transfer member as the image carrier, The present invention is also applicable to a case where the transfer member is a transfer material transfer belt or the like as a transfer member.

In the above embodiment, a two-component developer composed of a non-magnetic toner and a magnetic carrier is used as a developer used for development, and a two-component magnetic brush development method is used. Instead of this developer, magnetic one-component development using a magnetic toner may be used. Alternatively, non-magnetic one-component development may be performed using a non-magnetic toner and a developer carrier that does not include a magnet inside.

[0063]

According to the first to eighth aspects of the present invention, the adsorbing member is brought into contact with the object to be charged only when necessary, and is kept out of contact with the object to be charged. This has an excellent effect that wear of the suction member due to contact can be suppressed, and deterioration of image quality can be suppressed over a long period of time. Also, there is an excellent effect that the life of the suction member can be extended.

In particular, according to the invention of claim 2, there is an excellent effect that the toner contamination of the adsorption member can be suppressed, and the deterioration of the ability to adsorb and remove the discharge-producing substance due to the contamination can be suppressed.

In particular, according to the third aspect of the present invention, there is an advantage in that wear of the adsorption member is suppressed, and there is an excellent effect that the discharge generating substance can be efficiently removed.

In particular, according to the fourth aspect of the present invention, it is advantageous in that the wear of the attraction member is suppressed, and the discharge-producing substance on the surface of the charging object fixed with a strong adhesive force when left undisturbed is surely formed before image formation. There is an excellent effect that it can be removed.

In particular, according to the fifth and sixth aspects of the present invention, it is possible to remove the discharge-generating substance generated by the discharge before the discharge-generating substance is fixed on the charging target, and it is possible to more reliably remove the discharge-generating substance. There is an excellent effect that it can be done.

In particular, the invention according to claim 7 is advantageous in that wear of the suction member is suppressed, and the power supply is turned off.
There is an excellent effect that it is possible to remove a discharge-producing substance on the surface of the charging target that has adhered with a strong adhesive force during F.

In particular, according to the invention of claim 8, there is an excellent effect that the discharge generating substance can be removed over the entire surface of the circumferential portion to be charged.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a main part of a copying machine according to an embodiment.

FIG. 2 is an axial sectional view of a suction roller mounted on the copying machine.

FIG. 3 is a schematic configuration diagram showing a contact / separation mechanism of the suction roller.

FIG. 4 is a diagram showing a state in which the suction roller is separated from a photoconductor.

FIG. 5 is a flowchart according to an example of timing control of the contact / separation operation of the suction roller.

FIG. 6 is a diagram showing another configuration example of the charging unit.

FIG. 7 is a diagram illustrating another configuration example of the cleaning unit.

FIG. 8 is a diagram showing still another configuration example of the cleaning unit.

FIG. 9 is a diagram showing another combination of the charging unit and the cleaning unit.

FIG. 10 is a diagram showing still another combination of the charging unit and the cleaning unit.

FIGS. 11A and 11B are diagrams illustrating a photoconductor surface potential when a discharge-producing substance does not adhere to the surface of the photoconductor (a) and when the discharge-producing substance adheres to the surface (b).

FIG. 12 is a diagram showing a discharge-producing substance adsorption removing unit of an image forming apparatus proposed by the present applicant together with a photoconductor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Photoreceptor (charged object) 20 Corona discharger 21 Charging roller 30 Optical writing unit 40 Developing device 41 Developing roller 50 Transfer roller 60 Cleaning unit 61 Cleaning blade 63 Brush member 64 Cleaning roller 66 Seal brush 70 Static elimination lamp 80 Suction member ( 81 Surface layer 82 Lower layer 83 Hollow core shaft 91, 92 Registration roller 100 Fixing device 145 Solenoid 146 Link 147 Rotating pin 148 Swing pin 149 Arm 150 Frame after swing 151 Swing center shaft 152 Swing Front frame 153 Bearing 154 Pressure spring

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiromitsu Takagaki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock inside Ricoh Company (72) Inventor Kiyoshi Tanikawa 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh F-term (reference) 2H027 DA22 DA45 DD09 DE07 DE09 EA09 EC06 EC14 ED02 ED27 EE02 EE04 EF01 EF07 EF09 EF13 2H034 AA06 BA02 BA05 BC01 BC02 BC03 BC07 BC10 BF01

Claims (8)

[Claims] An image forming apparatus provided with a charging means for charging an object to be charged by a discharge, wherein the discharge generating material comprises an adsorbing member which contacts a surface of the object to be charged and adsorbs the discharge generating material generated by the discharge. It has a suction removing means, and is provided with a contacting / separating means of the suction member which can selectively take a state in which the suction member is in contact with the charging target and a state in which the suction member is separated from the charging target. Image forming device. 2. An image forming apparatus according to claim 1, further comprising control means for controlling said contact / separation means so that said attraction member is separated from said charging target during an image forming operation. An image forming apparatus comprising: 3. The image forming apparatus according to claim 2, wherein the control means performs a contact / separation operation of the adsorption member so as to adsorb the discharge generating substance every time a series of image forming operations is completed. An image forming apparatus characterized by controlling the contact / separation means. 4. An image forming apparatus according to claim 2, wherein said control means includes:
An image forming apparatus, comprising: controlling the contact / separation means so as to perform a contact / separation operation of the adsorption member so as to adsorb a discharge generating substance. 5. The image forming apparatus according to claim 1, wherein the object to be charged is an image carrier that carries an electrostatic latent image or a visible image, and the image carrier is used when performing an image forming operation continuously. When the surface between the rear end of the preceding image forming area and the front end of the subsequent image forming area of the surface of the surface faces the adsorbing member, the adsorbing member contacts and separates so as to adsorb the discharge generating substance. An image forming apparatus comprising: a control unit that controls the contact / separation unit so as to perform an operation. 6. The image forming apparatus according to claim 1, wherein the charging object is a transfer material conveying member that carries and conveys the transfer material, and when the image forming operation is performed continuously, the transfer material conveying member is used. When the surface between the rear end of the preceding transfer material and the front end of the subsequent transfer material among the surfaces of the transfer material opposes the adsorption member, the contacting / separating operation of the adsorption member is performed so as to adsorb the discharge generating material. An image forming apparatus, further comprising a control unit for controlling the contact / separation unit so as to perform the operation. 7. The image forming apparatus according to claim 1, further comprising driving means for rotating the charging target, and rotating the charging target in an initial operation after turning on the power so as to adsorb the discharge generating substance. The image forming apparatus further includes a control unit that controls the driving unit and the contact / separation unit so that the suction member contacts the charging target. 8. The image forming apparatus according to claim 1, wherein the charging target is a rotatable rotating body, and a contact time between the suction member and the charging target. An image forming apparatus, wherein the number of rotations of the object to be charged is one or more.