JP2002148906A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which can suppress lowering of removing ability of electric discharge products from an adsorption member to suppress lowering of image quality by facilitating the replacement and the maintenance of the attracting member. SOLUTION: The image forming apparatus has a corona discharger 20 which electrifies a photoreceptor drum 10 to be subjected to electrostatic charge by electric discharge and an attraction roller 80 which comes in contact with the surface of the photoreceptor drum 10 and attracts electric discharge products produced by the electric discharge of the photoreceptor drum 10, and the attraction roller 80 is constituted so as to be freely attached and detached to from the main body of the image forming apparatus.

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. 13 shows the photoconductor surface potential when the discharge product is not attached to the photoconductor surface (a) and when the discharge product is attached (b). As shown in FIG. 13 (a), when the discharge product is not adhered, 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. 13B, when a discharge product adheres to the surface of the photoreceptor, FIG.
As a result of exposing an area equal to 3 (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 off a discharge generating material. 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, it becomes necessary to remove such a discharge generating material by another method.

Japanese Patent Application Laid-Open No. Sho 60-49352 discloses an image forming apparatus capable of removing nitric acid or nitrate, which is a discharge-producing substance, from the surface of a photoreceptor without scraping the surface. This image forming apparatus includes:
A water cleaning means for cleaning the surface of the photoreceptor with water is provided, and the water cleaning means removes water-soluble nitric acid or nitrate.

[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. 14 shows an example of the construction of the discharge-producing substance adsorption / removal means 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 addition, the surface layer 82 to which the water has been supplied becomes gel-like, has an adhesive property, and maintains an appropriate amount of water. In the above configuration, when the photosensitive member 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 oozes out on the surface of the surface layer 81 due to the contact rotation. The exuded water is supplied to the surface of the photoconductor on the upstream side in the moving direction of the surface of the photoconductor from the entrance of the contact nip portion,
It 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 pressed in the contact nip portion to be adsorbed on the surface layer 81 having an adhesive property, or the suction roller 80 is exposed to light. In the vicinity of the outlet of the contact nip portion that is released from contact with the body 10, the water is absorbed by the surface layer 81 made of a water-absorbing material together with the water, and is removed from the surface of the photoconductor 10. As described above, by using the adsorption member 80 having a simple configuration including the surface layer 81 and the lower layer 82,
Since the discharge-producing substances can be removed, the size of the entire apparatus can be reduced as compared with the image forming apparatus described in Japanese Patent Application Laid-Open No. Sho 60-49352.

However, in the image forming apparatus having the suction member, the amount of discharge generated material retained on the surface or inside of the suction member increases with time, and toner or foreign matter adheres to the suction member. There has been a risk that the ability to remove the discharge-producing substance may decrease over time. As described above, when the ability to remove the discharge-producing substance is reduced, an abnormal image such as a flowing image is generated.

The present invention relates to the above-mentioned Japanese Patent Application No. 12-314217.
The purpose of the improvement is to make it easier to replace and maintain the adsorbing member, thereby suppressing a decrease in the ability of the adsorbing member to remove discharge-producing substances, and to improve image quality. An object of the present invention is to provide an image forming apparatus capable of suppressing a reduction in the 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: The image forming apparatus is characterized in that it has a discharge-product-substance adsorbing and removing means composed of an adsorbing member for adsorbing a discharge-producing substance generated by discharge, and the adsorbing member is configured to be detachable from the image forming apparatus main body.

In this image forming apparatus, since the suction member is detachable from the main body of the image forming apparatus, replacement and maintenance of the suction member are easy. Therefore, if the removal capacity of the discharge-producing substance decreases due to an increase in the amount of discharge-producing substance retained by the adsorbing member or the attachment of toner or foreign matter to the adsorbing member, the adsorbing member is removed and replaced with a new one. Or cleaning, it is possible to suppress a decrease in image quality.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, a determining means for determining a discharge-producing substance removing ability of the suction member, and a determination result based on the determination result of the determining means.
A notifying means for notifying the necessity of replacing or cleaning the suction member is provided.

In this image forming apparatus, the judgment means judges the ability of the adsorbing member to remove the discharge-producing substance, and notifies the user of the necessity of replacing or cleaning the adsorbing member based on the judgment result. The user can recognize the necessity of replacing or cleaning the suction member.

According to a third aspect of the present invention, in the image forming apparatus of the second aspect, there is provided an image forming frequency measuring means for measuring the cumulative number of image forming operations after the previous adsorption member replacement or cleaning, and based on the image forming frequency. The determination means is configured to determine the ability of the adsorption member to remove the discharge-producing substance.

Here, since the ability of the adsorbing member to remove the discharge-producing substance gradually decreases with its use, a certain degree of correlation is established between the degree of such reduction and the number of times of image formation. Therefore, in this image forming apparatus, the ability of the adsorption member to remove the discharge-producing substance is determined based on the number of times of image formation having such a correlation. For example,
The number of image formations N that does not significantly degrade the image quality is determined in advance by experiments or the like, and whether or not the ability to remove the discharge-generated substance of the adsorption member has been reduced is determined by whether or not the number of image formations N has been reached. Can be.

[0021]

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 is provided around the photoreceptor 10 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 which is a rotary member having a shape of a circle 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, the toner discharge screw 62, and the suction roller 80 are also driven to rotate in a predetermined direction.

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 with 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 means for removing and discharging the discharge-producing substance. FIG. 2 is a sectional view of the suction roller 80 in the axial direction. As shown in FIG. 2, the suction roller 80 of the present embodiment includes a surface layer 81 made of a highly water-absorbing material, a lower layer 82 made of a foamed or porous body that is an elastic and water-containing material, and a hollow core shaft. 83. 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 addition, the surface layer 82 to which the moisture is supplied.
Becomes gel-like, has stickiness and keeps moderate moisture. The water may be a fluid, a mist, or a vapor gas. Further, as disclosed in Japanese Patent Application No. 12-314217, a water tank as a water supply means is connected to the hollow core shaft 83 of the suction roller 80, and a plurality of water supply openings are formed in the core shaft 83. The water may be supplied from the supply tank to the lower layer 82 through the supply opening.

In the present embodiment, the hollow core shaft 83 of the suction roller 80 is connected to a driving motor (not shown), and the suction roller 80 is connected to the contact nip W, which is a contact area with the photosensitive member 10. The surface moves in the same direction as the surface moving direction of the photoconductor 10. Since the lower layer 82 of the suction roller 80 is an elastic body, a contact nip portion having a predetermined width is formed in a contact area with the photoconductor 10.

Next, a description will be given of the operation of adsorbing and removing a discharge-producing substance by the adsorbing roller 80 having the above-described structure. Photoconductor 1
When the suction roller 80 rotates in the direction indicated by the arrow in the figure when the suction member 80 comes into contact with the suction member 80, the water pressed from the lower layer 82 to the surface layer 81 oozes out onto the surface of the surface layer 81 due to the contact pressure. . 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 10 also 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 pressed in the contact nip portion to be adsorbed on the surface layer 81 having an adhesive property, or the suction roller 80 is exposed to light. In the vicinity of the outlet of the contact nip portion that is released from contact with the body 10, the water is absorbed by the surface layer 81 together with the water and is removed from the surface of the photoconductor 10.

In the above-described structure, 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.
It is possible to reduce the size of the entire apparatus as compared with the image forming apparatus described in JP-A-49352.

Here, there is a possibility that a part of the discharge-producing substance absorbed by the surface layer 81 and held on the surface and inside of the surface layer 81 may be exuded again with moisture when the suction roller 80 makes one rotation. When the holding amount of the discharge-producing substance of the suction roller 80 is within a predetermined amount, the discharge-producing substance, which is nitric acid or nitrate, can be dissolved in water in a large amount, so that even if it exudes with water, It is taken into the surface layer 81 again together with the next discharge product, and 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. However, when the retention amount of the discharge-producing substance in the suction roller 80 increases with time, the ability to remove the discharge-producing substance may decrease. Further, even when toner, foreign matter, or the like adheres to the adsorption path 80 over time, there is a possibility that the ability to remove the discharge-producing substance is reduced.

Therefore, in the present embodiment, the suction roller 80 is configured to be detachable from the copying machine main body, so that the replacement and maintenance of the suction roller 80 can be easily performed. Hereinafter, the attachment and detachment of the suction roller 80 from the copying machine main body will be described in detail.

First, the support mechanism of the suction roller 80 will be described. As shown in FIG. 3, both ends of the hollow core shaft 83 of the suction roller 80 are rotatably supported by the suction roller support holder 157 via bearings 153a and 153b. The pressing force of the bearings 153a and 153b is adjusted by the urging force of the pressing spring 154 so that the pressing force against the photoconductor 10 is kept constant.

On the other hand, as shown in FIG. 4, a guide holder 156 supporting the suction roller support holder 157 is rotatably mounted on a front side plate and a rear side plate (not shown) of the copying machine main body via support plates 150a and 150b. Supported swing center shaft 15
1 and is configured to be swingable about the swing center shaft 151. An arm 1 for transmitting the movement of the solenoid 145 and the link 146 to the swing center shaft 151 via a rotation pin 149 is provided at one end of the swing center shaft 151.
55 is fixed. The link 146 is rotatably attached to the solenoid 145 by a swing pin 148.

FIG. 5 shows the suction roller support holder 157.
FIG. 9 is a cross-sectional view in the suction roller axial direction in a state where is mounted on the guide holder 156. As shown in the drawing, leaf springs 158 and 159 are integrally attached to the suction roller support holder 157.
The suction roller 80 is positioned by engaging the projections 158 a of 58 with the recesses 156 a formed in the guide holder 156. Further, as shown in the drawing, by pushing down the leaf spring 158 in the vertical direction, the suction roller 80 together with the suction roller support holder 157 can be pulled out to the left in the drawing.

In the above configuration, when removing the suction roller 80 from the copying machine main body, first, the suction roller 80 is separated from the photoconductor 10. Specifically, the solenoid 145 that has sucked the link 146 in the direction of arrow C in the drawing to turn off the solenoid 145 in order to perform the operation of removing the discharge-producing substance turns the arm 149 by the separation spring 1148 fixed to the main body side plate (not shown). Pull in the direction of the middle arrow D. As a result, the suction roller 80 rotates in the direction of the arrow E in the figure around the swing center shaft 151, so that the suction roller 80 can be separated from the photoconductor 10 as shown in FIG. The separating operation may be manually performed by a user, or may be performed, for example, such that the suction roller 80 is automatically separated from the photosensitive member 10 at a timing when the image forming operation is completed and the rotation of the photosensitive member 10 is stopped. Alternatively, ON / OFF of the solenoid 145 may be controlled.

In this state, the user grasps the handle 160 of the leaf springs 158 and 159 attached to the suction roller support holder 157, and pushes down the leaf spring 158 while moving the leaf spring 158 toward the front of the apparatus (left side in the figure). By pulling out, the suction roller 80 together with the suction roller support holder 157 is drawn.
Can be removed from the copier body.

When the suction roller 80 is mounted on the copying machine main body, the user operates the handle 16 of the leaf springs 158 and 159.
0, and while pressing down the leaf spring 158, the suction roller support holder 157 is inserted into the inner side of the apparatus (right side in the figure), and the suction roller support holder 157 is moved to the guide holder 156.
Release your hand when it comes into contact with the projection at the far end (left end in the figure). When the hand is released, the protrusion 158 of the leaf spring 158 is released.
a engages with the concave portion 156a of the guide holder 156, and the mounting of the suction roller 80 on the copying machine main body is completed.

As described above, by making the suction roller 80 detachable from the copying machine, replacement and maintenance of the suction roller 80 can be easily performed. Therefore, when the discharge generation material holding capacity of the suction roller 80 increases or toner or foreign matter adheres to the suction roller 80 and the ability to remove the discharge generation material decreases, the suction roller 80 is removed and a new one is removed. By exchanging with a material or cleaning, it is possible to suppress a decrease in image quality.

The timing of replacing or cleaning the suction roller 80 described above is determined by a control unit (not shown) provided in the copying machine of the present embodiment. Therefore, next, the operation of the control unit that determines the time to replace or clean the suction roller 80 will be described. FIG. 7 is a flowchart showing the operation of the control unit. The copying machine according to the present embodiment includes a counter (not shown) serving as an image forming number measuring unit for measuring the number of copies (number of copies), and a memory (not shown) for storing the number of developed sheets counted by the counter. .

First, the counter counts the number of copies up to a predetermined number of copies set in advance, and determines whether the number of copies has reached the predetermined number of copies due to the user's use over time (S1). When the number of copies reaches a predetermined number, the solenoid 145 is turned off when the rotation of the photoconductor 10 is stopped after the series of copying operations is completed, and the suction roller 8 is turned off.
0 is separated from the photoconductor 10 (S2). Next, an indication of "replacement / cleaning of the attraction roller" for notifying the necessity of replacement or cleaning of the attraction roller 80 is displayed on an operation panel (not shown) as a notifying means (S3).

The above-mentioned predetermined number of copies is determined in advance by experiments or the like so that the number N of copies does not significantly degrade the image quality. For example, in the copying machine shown in FIG.
When the suction roller 80 (with a thickness of the surface layer 81 of 2 mm, a thickness of the lower layer 82 of 2 mm, and a diameter of the hollow core shaft 83 of φ8) is attached, the ability to remove discharge products is reduced after about 50,000 sheets, and image quality is reduced. Was confirmed. In this case, the predetermined number of copies may be set to a number less than 50,000,
When the frequency of replacement or cleaning increases, cost and maintainability deteriorate. Considering these points, 5
It is preferable to set it to 10,000 sheets. The suction roller 80
It is thought that if the diameter is large, the predetermined number of copies can be set to 50,000 or more, but a wide space must be secured around the photoreceptor 10. Therefore, it is necessary to appropriately select the suction roller 80 in consideration of such points.

As described above, in this embodiment, under the control of the control unit, the suction roller 80 is provided on the operation unit panel of the copying machine.
Is displayed to notify the user of the necessity of replacement or cleaning of the suction roller 80, so that the user can recognize the necessity of replacement or cleaning of the suction roller 80, and the replacement or cleaning of the suction roller 80 can be performed in a timely manner. it can.

In the above embodiment, as the super absorbent material constituting the surface layer 81, polyalkyl oxide such as polyethylene oxide, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl butyral,
Polyacrylamide, polypropylene glycol, glue, gelatin, casein, albumin, alginic acid, sodium alginate, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl ether, polyvinyl methyl cellulose, polyethylene glycol, glucose, xylose, sucrose, maltose, arabinose, α-cyclodextrin And copolymers such as starch and the like, graft polymers, crosslinked products and the like. 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 material 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 thereto. For example, as a charging unit, a contact charging type charging roller 21 as shown in FIG. 8 can be applied. As a cleaning means, a brush member 63 as shown in FIG.
A magnetic brush cleaning method using a cleaning roller 64 having a built-in magnetism as shown in FIG.
The brush-like member 66 in FIG. 10 is a seal brush for preventing the developer from leaking in the cleaning device 60. Further, as shown in FIG.
Various combinations are possible, such as using a brush and a brush member 63, or using a charging roller 21 and a cleaning roller 64 of a magnetic brush cleaning type as shown in FIG.

In the above embodiment, the case where the object to be charged is a photoconductor as an image carrier has been described. However, the present invention relates to a case where the object to be charged is an intermediate transfer body as an image carrier, The present invention is also applicable to a case where the transfer member is a transfer material transfer belt or the like.

In the above-described 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.

[0057]

According to the first to third aspects of the present invention, the replacement and maintenance of the suction member can be easily performed, so that the deterioration of the discharge member removing ability of the suction member is suppressed and the image quality is lowered. Has an excellent effect that it is possible to suppress

In particular, according to the second aspect of the present invention, the user can recognize the necessity of replacement or cleaning of the suction member, so that the replacement or cleaning of the suction member can be performed in a timely manner, and image quality can be improved. There is an excellent effect that reduction can be suppressed.

According to the third aspect of the present invention, every time the number of image formations reaches a predetermined number set in advance, the user is prompted to replace or clean the suction member, so that the replacement or the suction member is periodically performed. Cleaning can be done,
There is an excellent effect that deterioration in image quality can be suppressed.

[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 an explanatory view illustrating a support mechanism (support holder) of the suction roller.

FIG. 4 is an explanatory diagram illustrating a guide holder that supports the support holder.

FIG. 5 is a cross-sectional view in the suction roller axial direction in a state where the support holder is mounted on a guide holder.

FIG. 6 is an explanatory diagram illustrating a state in which a suction roller is separated from a photoconductor.

FIG. 7 is a flowchart showing the operation of the control unit of the copying machine.

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

FIG. 9 is a diagram illustrating another configuration example of the cleaning unit.

FIG. 10 is a diagram showing still another configuration example of the cleaning unit.

FIG. 11 is a diagram showing another combination of a charging unit and a cleaning unit.

FIG. 12 is a diagram showing still another combination of a charging unit and a cleaning unit.

FIGS. 13A and 13B are diagrams showing the 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. 14 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 70 Static elimination lamp 80 Suction roller (Discharge generating material) Suction removal means) 81 Surface layer 82 Lower layer 83 Hollow core shaft 91, 92 Registration roller 100 Fixing device 145 Solenoid 146 Link 148 Swing pin 149 Rotating pin 150 Support plate 151 Swing center shaft 153 Bearing 154 Pressurizing spring 155 Arm 156 Guide Holder 157 Suction roller support holder 158 Leaf spring

Continued on the front page (72) Inventor Hiromitsu Takagaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kiyoshi Tanigawa 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Masahiko Akato 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H003 AA18 BB11 CC01 EE00 2H027 DA45 DE07 GB07 GB08 HB02 HB16 HB19 JA01 JA11 JC01 JC02 2H034 AA06 FA11

Claims (3)

[Claims] An image forming apparatus provided with a charging means for charging an object to be charged by discharge, wherein a discharge generating material adsorbing member is provided which is in contact with a surface of the charging and adsorbs a discharge generating material generated by the discharging. An image forming apparatus comprising: a removing unit; and wherein the suction member is configured to be detachable from the image forming apparatus main body. 2. An image forming apparatus according to claim 1, wherein said means for judging the ability of said adsorbing member to remove discharge-producing substances, and the necessity of replacing or cleaning the adsorbing member based on the judgment result of said judging means. An image forming apparatus, comprising: a notifying unit for notifying. 3. An image forming apparatus according to claim 2, further comprising: an image forming frequency measuring means for measuring the cumulative number of image forming operations after the previous replacement or cleaning of the attraction member, and based on the number of image forming operations, the at least one adsorbing member. An image forming apparatus, wherein the determining means is configured to determine the discharge-product removing ability of the image forming apparatus.