JP4874733B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer. More specifically, the present invention relates to an image forming apparatus having a cleaning unit that visualizes an electrostatic latent image formed on a photoreceptor with toner, transfers the toner image onto a transfer material, and then removes toner remaining on the photoreceptor. Is.

  In the image forming apparatus, a cleaning device for cleaning the transfer residual toner remaining on the surface of the image carrier that has passed the transfer position for transferring the toner image from the image carrier to a recording sheet or the like is required. In addition, when adopting a configuration in which a toner image is transferred from an image carrier to a recording paper or the like via an intermediate transfer member, a cleaning device for cleaning the intermediate transfer member is provided in addition to a cleaning device for cleaning the image carrier. I need it.

  As these cleaning devices, a scraping type and an electrostatic transfer type are known. In the scraping method, a cleaning member such as a cleaning blade or a rotationally driven cleaning brush is brought into contact with the endlessly moving surface of the image carrier or intermediate transfer member. Then, the toner is scraped off from the surface of the image carrier by the cleaning member at the contact portion between the cleaning member and the image carrier. In the electrostatic transfer method, a cleaning bias having a polarity opposite to that of the toner is applied to the cleaning member while the surface of the cleaning member is moved endlessly by rotation driving or the like. Then, the toner is transferred from the surface of the image carrier to the surface of the cleaning member by electrostatic force.

  On the other hand, in recent years when high image quality is being promoted, instead of the toner by the pulverization method, the toner by the polymerization method having a smaller particle diameter and excellent sphericity is becoming mainstream. By using the toner by the polymerization method, it is possible to form a high-quality image while suppressing the disturbance of the high-resolution small-diameter dots compared to the case of using the toner by the pulverization method.

  When such a polymerized toner is used, it is difficult to reliably clean the toner from the surface of the image carrier by the scraping-type cleaning. This is because the toner particles produced by the polymerization method having a small particle size and excellent sphericity pass through a slight gap formed between the blade and the image carrier or do not sufficiently contact the brushed brush. Because.

  On the other hand, in the electrostatic transfer type cleaning, the toner by polymerization is transferred from the surface of the image carrier to the cleaning member by electrostatic force even if the cleaning member and the toner on the surface of the image carrier are not in sufficient contact. be able to. However, in the transfer residual toner adhering to the image carrier, there are reversely charged toner particles that are charged to a polarity opposite to the normal polarity due to charge injection during the transfer process. . Therefore, in the electrostatic transfer method, it becomes difficult to clean the reversely charged toner particles.

  Therefore, in Patent Document 1, the configuration shown in FIG. 2 is adopted for the purpose of electrostatically transferring both the normal polarity toner particles and the reversely charged toner particles contained in the transfer residual toner to the electrostatic transfer type cleaning member. An image forming apparatus has been proposed. That is, the polarity control means 30 for controlling the polarity of the toner is provided on the downstream side of the transfer means 25 in the rotation direction of the image carrier and on the upstream side of the fur brush 31 that is an electrostatic cleaning member in the rotation direction of the image carrier. . As a result, before the transfer residual toner reaches the position facing the fur brush 31, charge is injected into the transfer residual toner by the polarity control means 30, and the transfer residual toner is aligned with the normal polarity by transferring the polarity of the transfer residual toner to the normal polarity. Is electrostatically attracted to the fur brush 31 and removed from the surface of the image carrier 21.

JP 2004-239999 A

  However, when the previous image forming operation is completed and the image carrier 21 stops rotating, the transfer residual toner that has not yet been cleaned even though the polarity is controlled is transferred to the polarity control means 30 on the image carrier 21 and the fur. It remains between the brush 31. When these untransferred toners are left on the image carrier 21, the charge disappears with the passage of time, and the charge amount of the untransferred toner decreases. If the charge amount of the transfer residual toner decreases in this way, even if a voltage is applied to the fur brush 31 at the start of the next image forming operation, the charge amount of the transfer residual toner decreases, so that the transfer residual toner is reduced. The toner is not attracted to the fur brush 31 and the transfer residual toner cannot be cleaned from the image carrier 21. Therefore, at the next image formation, the surface of the image carrier is charged while the transfer residual toner that could not be cleaned by the fur brush 31 remains on the image carrier 21. As a result, there is a problem in that the charged state is different between the portion where the transfer residual toner remains on the surface of the image carrier and the portion where there is no transfer residual toner, and an abnormal image is generated during the next image formation.

  The present invention has been made in view of the above problems, and the object of the present invention is to contact the cleaning object contact point between the polarity control unit on the object to be cleaned and the electrostatic cleaning unit after the end of the previous image forming operation. It is an object of the present invention to provide an image forming apparatus capable of suppressing the occurrence of an abnormal image at the next image formation caused by toner remaining in the meantime.

In order to achieve the above object, the invention according to claim 1 is directed to a cleaning object that can be rotated forward and backward in the circumferential direction, and a toner that is in contact with the surface of the cleaning object and that adheres to the cleaning object. Electrostatic cleaning means for removing the toner, a polarity control means for controlling the polarity of the toner provided upstream of the electrostatic cleaning means in the normal rotation direction of the cleaning object, and the cleaning object of the polarity control means In an image forming apparatus provided with a charging means for charging the member to be cleaned provided upstream of the normal rotation direction and upstream of the member to be cleaned in the normal rotation direction of the electrostatic cleaning unit, Until the object to be cleaned is longer than the circumference of the object to be cleaned between the contact points of the object to be cleaned between the polarity control unit and the electrostatic cleaning unit by the normal rotation. A control means for controlling so as to rotate in the opposite direction of the direction, the polarity control means includes characterized in that said control means when performing the control, and is configured so as to be separated from該被cleaning member To do.
Further, it the invention of claim 2, the image forming apparatus according to claim 1, said charging means, when said control means performs the control, is not conducted charged to the surface of the object to be cleaned body It is characterized by.
According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect , an image carrier that carries an image and a developing unit that develops an image on the image carrier with toner and forms a toner image. The object to be cleaned is the image carrier.
According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect , wherein the image bearing member for carrying the image and the developing means for developing the image on the image bearing member with toner to form a toner image. The object to be cleaned is the image carrier, and A represents the circumference of the image carrier between the contact points of the polarity control means and the electrostatic cleaning means. When the circumference of the elephant carrier between the contact points of the image carrier and the developing means is B, the relationship of A <B is satisfied.
According to a fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect of the present invention, the image forming apparatus further includes a transfer unit that transfers the toner image on the image carrier to the transfer target. When the control means performs the above-described control, it is configured not to come into contact with the transfer object.
According to a sixth aspect of the present invention, in the image forming apparatus according to the third, fourth, or fifth aspect , the developing unit does not supply the developer onto the image carrier when the control unit performs the control. It is characterized by this.
According to a seventh aspect of the present invention, in the image forming apparatus according to the third, fourth, fifth, or sixth aspect , the image carrier having a protective layer containing a filler (particulate matter) is used. It is what. According to an eighth aspect of the present invention, in the image forming apparatus of the third, fourth, fifth or sixth aspect , the image carrier is an organic photoreceptor having a surface layer reinforced with a filler, or a cross-linked charge transport. It is an organic photoreceptor using the material, or an organic photoreceptor having both characteristics.
According to a ninth aspect of the present invention, in the image forming apparatus according to the third, fourth, fifth, or sixth aspect , the image bearing member having a surface layer made of amorphous silicon is used.
According to a tenth aspect of the present invention, in the image forming apparatus according to the third, fourth, fifth, sixth, seventh, eighth or ninth aspect , a multicolor image is formed by a developing unit comprising a plurality of developing units on one image carrier. It is characterized by forming.
The invention according to claim 11 is the image forming apparatus according to claim 3, 4, 5, 6 , 7, 8, or 9 , wherein the image forming apparatus comprises a plurality of image forming portions each composed of one image carrier and one developing device, A multicolor image is formed by superimposing toner images formed by the plurality of image forming units.
The invention of claim 12 is the image forming apparatus according to claim 3, 4, 5, 6 , 7, 8 or 9 , selected from the charging means, the developing means, the polarity control means, and the electrostatic cleaning means. And a process cartridge that integrally supports the image carrier and is detachable from the main body of the image forming apparatus.
The invention of claim 13 is the image forming apparatus according to claim 1 or 2, developing an image bearing member for bearing an image, the image on the image bearing member with toner to form a toner image developing Means, an intermediate transfer member for carrying the toner image transferred from the image carrier, a first transfer means for transferring a toner image from the image carrier to the intermediate transfer member, and a recording member from the intermediate transfer member And a second transfer means for transferring the toner image to the toner image, wherein the member to be cleaned is the intermediate transfer member.
The invention of claim 14 is the image forming apparatus according to claim 1 or 2, developing an image bearing member for bearing an image, the image on the image bearing member with toner to form a toner image developing And a transfer carrier that conveys a recording member onto which the toner image on the image carrier is transferred to a transfer position facing the surface of the image carrier. It is a transfer conveyance body.
According to a fifteenth aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelve, thirteen, or fourteenth aspect, The control is performed after the image forming operation is completed.
According to a sixteenth aspect of the invention, in the image forming apparatus of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, or fourteenth aspect, the control means includes: before the image forming operation start is characterized in the der Turkey performs the above control.
According to a seventeenth aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelve, thirteen, or fourteenth aspect, The above control is performed after warm-up.
The invention according to claim 18 is the image forming apparatus according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17 . A toner having a shape factor SF-1 in the range of 100 to 150 is used as the toner.

In the present invention, the rotation of the cleaning target can be controlled in the direction opposite to the normal rotation direction so that the transfer residual toner moves to the upstream side of the cleaning target normal rotation direction of the polarity control means. As a result, the transfer residual toner is again passed through the polarity control means and charged, so that the electrostatic cleaning means can electrostatically adsorb the transfer residual toner, so that the transfer residual toner is removed from the object to be cleaned. can do.

  As described above, according to the present invention, after the previous image forming motion creation, the next image forming time caused by the toner remaining between the contact points of the cleaning object between the polarity control unit and the electrostatic cleaning unit on the cleaning object. There is an excellent effect that the abnormal image can be suppressed.

Hereinafter, an embodiment in which the present invention is applied to a printer which is an image forming apparatus will be described. FIG. 3 is an overall configuration diagram of the printer according to the present embodiment.
Around the photoconductor 1 as an image carrier, a charging device 2 that charges the surface of the photoconductor 1 with a charging roller or the like, and an exposure device 3 that forms a latent image on the uniformly charged surface of the photoconductor 1 with a laser beam L. A developing device 4 as a developing unit that forms a toner image by attaching a charged toner to the latent image on the photosensitive member 1, and a transfer device 5 that transfers the toner image formed on the photosensitive member 1 to a transfer sheet. A cleaning device 7 for removing the toner remaining on the photosensitive drum 1 after the transfer and a neutralizing device 8 for removing the residual potential on the photosensitive member 1 are arranged in this order.

  In the printer configured as described above, the photosensitive drum 1 whose surface is uniformly charged by the charging device 2 forms an electrostatic latent image by the exposure device 3 and forms a toner image by the developing device 6. The toner image is transferred by the transfer device 5 from the surface of the photosensitive drum 1 to the transfer paper conveyed from the paper feed cassette 8.

  Below the transfer device 5, there is disposed a paper feed cassette 8 for storing a plurality of transfer sheets as recording bodies. The paper feed cassette 8 rotates the paper feed roller pressed against the uppermost transfer paper at a predetermined timing, and feeds the transfer paper to the paper feed conveyance path. In the paper feed conveyance path, the transferred transfer paper passes through a plurality of conveyance roller pairs 13 and is then sandwiched between the rollers of the registration roller pair 14 and stopped. The registration roller pair 14 feeds the sandwiched transfer paper toward the transfer nip between the transfer prosecution 5 and the photoconductor 1 at a timing at which it can be superimposed on the toner image formed on the photoconductor 1 as described above. . As a result, the toner image on the photoconductor 1 and the transfer paper fed by the registration roller pair 14 are brought into close contact with each other at the transfer nip. Then, it is electrostatically transferred onto the transfer paper due to the influence of the transfer voltage.

  A paper transport belt 12 is wound around the transfer device 5, and the paper transport belt 12 is stretched around the transfer device 5 and a driving roller and moves endlessly counterclockwise in the drawing. Further, a fixing device 9 and a discharge roller pair 10 are sequentially disposed on the left side of the paper conveying belt 12. The transfer paper on which the toner image is electrostatically transferred is sent onto the paper transport belt 12 and then enters the fixing device 9. The transfer paper that has entered the fixing device 9 is subjected to heat treatment and pressure treatment. As a result, the toner is thermally melted under pressure, and the toner image is fixed on the transfer paper. Then, the transfer sheet is discharged from the fixing device 9 to the outside of the apparatus through the discharge roller pair 10.

  The toner remaining on the photosensitive drum without being transferred is collected by the cleaning device 7. The photoreceptor 1 from which the residual toner has been removed is initialized by the charge eliminating lamp 8 and used for the next image forming process. Further, the toner transferred onto the transfer / conveying belt is removed from the transfer / conveying belt by the belt cleaning device.

  In the present embodiment, as shown in FIG. 4, the photosensitive member 1, a developing device 6, a charging device 2, a cleaning device 7 and the like disposed around the photosensitive member 1 are integrated as a process cartridge 100. The process cartridge 100 is detachable from the printer body. Therefore, when the life of a component housed in the process cartridge 100 is reached or maintenance is required, the process cartridge 100 may be replaced, which improves convenience.

  Next, a series of image forming processes will be described in detail with reference to FIG. When the image forming operation is started, a predetermined voltage or current is sequentially applied to the charging device 2, the developing device 4, the transfer device 5 and the cleaning unit in the drawing at predetermined timings, and at the same time, the photoreceptor 1 and the charging device. 2. The developing device 4, the transfer device 5, and the cleaning unit start predetermined operations. The photosensitive member 1 is uniformly negatively charged (-900 V) by the charging device 2 arranged oppositely, and a latent image is formed (black solid potential is -150 V) by the exposure device 3. The latent image is developed by the developing device 4 (development bias is −600 V), and a toner image is formed on the photoreceptor 1. The toner image is fed from the paper cassette 8 between the photosensitive member 1 and the transfer device 5, and the toner image is transferred (+10 μA applied) onto the supplied transfer paper in synchronization with the leading edge of the image. . The transfer paper is output through the fixing device 9. Usually, the photosensitive member 1 is in the form of a drum or a belt, and in order to continuously perform an image forming process, the transfer residual toner remaining on the photosensitive member 1 after passing through the transfer device 5 is exposed to a cleaning means. Remove from body 1.

Next, characteristic parts of the present embodiment will be described. Examples of various devices and various members that affect image formation in the present embodiment include the following.
Examples of the charging device 2 include a proximity roller charging method or a contact roller charging method in which a voltage of DC or DC + AC is applied, and a corona charging method, a magnetic brush charging method, a blade charging method, and the like. . The corona charging method has a large amount of ozone generation and a large applied voltage, but the influence of discharge on the surface of the photoconductor 1 is small. Therefore, in order to design an image forming apparatus aiming at the long life of the photoconductor 1, It is valid. The roller charging method is desirable to be mounted in the image forming apparatus from the viewpoint that the amount of ozone generated is small and the applied voltage is small. However, the influence of the discharge on the photoconductor 1 is large and the life of the photoconductor 1 is shortened. The roller charging method includes a non-contact charging method made of a rubber material and a non-contact charging method made of a resin material. When a non-contact charging method made of a resin material is used, the rigidity in the roller axis direction is maintained. In addition, since the gap with the photoconductor 1 can be ensured with higher accuracy, it is more desirable in terms of less adverse effects such as contamination of the surface of the charging roller. Further, when DC is applied, the influence of the discharge on the photosensitive member 1 can be reduced, but the uniform chargeability of the photosensitive member 1 is inferior. On the other hand, when AC is superimposed on DC, the influence of the discharge on the photoreceptor 1 becomes very large and the amount of ozone generated increases, but the uniform chargeability of the photoreceptor 1 is excellent. The charging device 2 and the charging method are optimally selected depending on the image forming apparatus, but the charging device 2 in this embodiment is not limited.

Next, the exposure apparatus 3 includes an exposure method using an LD, an LED lamp, and a xenon lamp.
Further, examples of the developing device 4 include a developing method using a one-component developing unit in which only toner is mounted in the developing device 4 and a two-component developing unit that uses toner and a carrier mixed for development. The toner described here refers to a toner prepared by a pulverization method or a polymerization method. However, even a toner prepared by a polymerization method can be cleaned with a conventional cleaning blade.
Examples of the transfer device 5 include a transfer method using a transfer belt, a transfer charger, a transfer roller, and a transfer brush.

The cleaning means includes a polarity control member 10 and an electrostatic cleaning member 11, each of which is configured as follows.
The transfer residual toner is charged positively or negatively by the polarity control member 10, and the polarity thereof is aligned. The mechanism in which the polarities are aligned at this time is frictional charging by contact between the polarity control member 10 and the toner, or charge injection. The transfer residual toner may be aligned with either polarity. In the case of frictional charging, the polarity after frictional charging changes depending on the frictional charging series of the material that contacts the toner. In the case of charge injection, the polarity is aligned to positive when the positive polarity is applied to the polarity control member 10 and negative when the negative polarity is applied. Here, the voltage applied to the polarity control member 10 may be only DC or a voltage obtained by superimposing AC on DC. However, by superimposing AC on DC, the toner polarity can be made more uniform. .
In FIG. 1, negative polarity is applied to the polarity control member 10, but positive polarity may be applied. However, at that time, the voltage applied to the electrostatic cleaning member 11 (recovery roller 12) is negative. In FIG. 1, the polarity control member 10 is shown as a blade, but the polarity control member 10 is a blade, brush, roller, belt, or the like made of a conductive material, such as a magnetic brush.
When a conductive blade is used, it contacts with the counter or the trailing with respect to the rotation direction of the photosensitive member 1. The elastic modulus is preferably 20 to 80%, the thickness is 1 to 6 mm, and the contact angle with respect to the photosensitive member 1 is preferably 15 to 45 ° in the case of a counter and 90 to 175 ° in the case of trailing.
Moreover, when a brush is used, the thing by which the electroconductive fine particles 15 were disperse | distributed inside the brush fiber 14 is mentioned. Examples of the conductive fine particles 15 include those dispersed throughout the inside of the fiber as shown in FIG. 5, those dispersed only within the fiber outer periphery as shown in FIG. 6, and those dispersed only inside the fiber as shown in FIG.
Moreover, when a roller is used, a conductive elastic roller or a conductive hard roller can be used. These rollers may be composed of a plurality of layers having different resistance values in the radial direction.
Moreover, when a belt is used, an electroconductive elastic belt is mentioned. This belt may be composed of a plurality of layers having different resistance values in the thickness direction.

  The transfer residual toner having the same polarity is cleaned from the photosensitive member 1 by the electrostatic cleaning member 11. Here, the voltage application to the electrostatic cleaning member 11 can be realized by the voltage application to the collection roller 12. Therefore, the electrostatic cleaning member 11 needs to be made of a conductive material. The toner adjusted to either polarity by the polarity control member 10 can be cleaned by applying a reverse polarity to the electrostatic cleaning member 11.

The toner cleaned by the electrostatic cleaning member 11 in this manner is collected by the collection roller 12. Here, a belt-shaped collection belt may be used as the collection roller 12. A voltage having a positive or negative polarity is applied to the collection roller 12. As a result, a voltage can be applied to the electrostatic cleaning member 11. Here, the collection roller 12 or the collection belt is preferably provided with a resistance layer of about 10 ⁹ to 10 ^{13 on the} surface layer thereof because toner injection charging that occurs during toner collection becomes a problem. Further, the surface of the collecting roller 12 is desired to have a low friction coefficient in order to improve the toner scraping performance by the blade 13, and the friction coefficient μ in the Euler belt method friction coefficient measurement method is 0.3 or less. Is desired. Further, as the surface properties, it is desirable that the water contact angle is 90 ° or less and the surface roughness Ra is 0.3 or less. The toner collected by the collection roller 12 in this way is removed from the collection roller 12 by the blade 13. Although described as a blade 13 in FIG. 1, if the toner can be scraped off from the collection roller 12, the blade 13 is not necessary, and may be a mylar, flicker, belt, roller, or the like. When the blade 13 is used, the material thereof is made of polyurethane rubber, and abuts against the rotation direction of the collection roller 12 by a counter or trailing. The elastic modulus is preferably 20 to 80%, the thickness is 1 to 6 mm, and the contact angle with respect to the photosensitive member 1 is preferably 15 to 45 ° in the case of a counter and 90 to 175 ° in the case of trailing.

  However, even if the transfer residual toner on the photosensitive member 1 is cleaned by the above-described method, when the photosensitive member 1 stops rotating after the previous image forming operation, the polarity control member 10 and the electrostatic cleaning member 11 Since the charge amount of the toner remaining therebetween decreases with time (or becomes uncharged), it cannot be cleaned by the electrostatic cleaning member 11 at the start of the next image forming operation. Therefore, during the next image forming operation, an abnormal image is generated by the toner that remains on the photoreceptor 1 and is not cleaned, and contamination of the charging device 2 and the photoreceptor 1 is accelerated. Therefore, in this embodiment, even if the charge amount of the toner remaining between the polarity control member 10 and the electrostatic cleaning member 11 is reduced, an abnormal image is not output on the printed image when the next image is formed as follows. I have to.

That is, a control unit (not shown) that rotates the photoreceptor 1 in reverse is mounted in the image forming apparatus, and the photoreceptor 1 is configured to rotate in the direction opposite to the rotation direction during image formation, that is, the normal rotation direction. As a result, the toner that remains between the contact points of the polarity control member 10 and the electrostatic cleaning member 11 on the photoreceptor 1, and the toner whose charge amount has decreased or has become 0 is removed from the upstream side of the polarity control member 10. Can be moved to. Therefore, the toner whose charge amount has decreased or has become zero can be passed again through the polarity control member 10 during the next image formation. Therefore, by applying a voltage to the polarity control member 10 during the next image forming operation, the toner remaining on the photoreceptor 1 can be charged again, and the voltage is applied to the electrostatic cleaning member 11 and driven. As a result, the toner can be cleaned. Therefore, since the image forming operation is not performed using the toner remaining between the contact points of the polarity control member 10 and the electrostatic cleaning member 11 on the photoreceptor 1, no abnormal image is generated. Here, when the photosensitive member 1 is reversely rotated, only the photosensitive member 1 needs to be reversely rotated. Therefore, exposure by the exposure device 3, voltage application to the polarity control member 10, voltage application to the electrostatic cleaning member 11, driving Do not need to do.
If the amount of movement of the photosensitive member 1 is shorter than the peripheral length of the photosensitive member between the contact points of the polarity control member 10 and the electrostatic cleaning member 11, all the toner whose charge amount has decreased or has become zero is again removed. Since the polarity control member 10 cannot be passed, all the remaining toner cannot be cleaned during the next image forming operation, and an abnormal image is generated. For this reason, the minimum movement amount of the photosensitive member 1 needs to move by the peripheral length of the photosensitive member between the contact points of the polarity control member 10 and the electrostatic cleaning member 11.

Further, in this embodiment, as shown in FIG. 1, the peripheral length of the photosensitive member between the photosensitive member contact points of the polarity control member 10 and the electrostatic cleaning member 11 is A, and the photosensitive member contact point of the charging device 2 and the developing device 4. When the circumferential length of the photosensitive member is B, the relationship between A and B satisfies A <B.
When A ≧ B, when the photosensitive member 1 is rotated reversely by the peripheral length of the photosensitive member between the contact points of the polarity control member 10 and the electrostatic cleaning member 11, the photosensitive member immediately before the reverse rotation of the photosensitive member 1 is detected. The contact point between the body 1 and the developing device 4 is returned to the upstream side of the charging device 2. For this reason, toner adheres to the surface of the photosensitive member 1 when passing through the contact point with the developing device 4, so that at the end of the reverse rotation of the photosensitive member 1, the photosensitive member to which the toner has adhered upstream from the charging device 2. One surface will return. When the next image forming operation is started in this state, the charging device 2 charges the surface of the photosensitive member 1 to which the toner adheres, and the charging device 2 cannot uniformly charge the surface of the photosensitive member 1. End up. Therefore, by configuring the image forming apparatus so that the relationship between A and B satisfies A <B, the surface of the photoreceptor 1 that has been in contact with the developing device 4 is not returned to the upstream side of the charging device 2, so that charging is always performed. The apparatus 2 can charge the toner-free surface of the photoreceptor 1 and can perform uniform charging.

  When a conductive blade is used as the polarity control member 10, the conductive blade comes into contact with the photoconductor 1 by trailing when the photoconductor 1 rotates in the reverse direction. At this time, a small amount of toner remaining between the contact points of the polarity control member 10 and the electrostatic cleaning member 11 on the photosensitive member 1 is damped and retained by the conductive blade during the reverse rotation. The polarity of the toner that could not come into contact with the conductive blade cannot be controlled. Therefore, even if the next image forming operation is performed, it cannot be cleaned by the electrostatic leaning means. Therefore, when the photosensitive member 1 is rotating in the reverse direction, the conductive blade is separated from the photosensitive member 1 to prevent the toner from being blocked by the polarity control member 10, and all the toner passes through the polarity control member 10 again. Since all the toner can be charged again and can be cleaned, an abnormal image is not generated. Here, it is necessary that the conductive blade is always separated from the photoconductor 1 during one rotation of the photoconductor. A timing chart of contact and separation of the conductive blade is shown in FIG.

Further, when it is difficult to separate the polarity control member 10 due to the convenience of the apparatus configuration, the following alternative means may be used. When the polarity control member 10 is a conductive blade (trailing or counter), the contact pressure may be reduced.
When the polarity control member 10 is a conductive brush, the rotation of the conductive brush is controlled so that the rotation direction is in contact with the reverse rotation direction of the photosensitive member 1 by the trailing, and the toner is controlled by the polarity control member 10. You may make it easy to move to the upstream side.

  Further, it is necessary that the charging device 2 does not charge the surface of the photosensitive member 1 when the photosensitive member 1 rotates in the reverse direction. When the corona charging device 16 is used, the surface of the photosensitive member 1 is excessively charged by the amount of movement that the photosensitive member 1 is rotated in the reverse direction. This is because it becomes uniform. In addition, when a contact or contact roller charging device is used, the surface of the photoreceptor 1 is scraped by a discharge generated when a voltage is applied to charge the surface of the photoreceptor 1.

  Further, it is necessary not to develop toner on the photosensitive member 1 when the photosensitive member 1 is rotated forward and backward. As a result, toner is not consumed when it has nothing to do with image formation, and toner consumption can be reduced.

  Next, when the photosensitive member 1 comes into contact with the transfer target during the reverse rotation of the photosensitive member 1, the toner remaining on the photosensitive member 1 and not cleaned by the electrostatic cleaning member 11 is transferred to the transfer target. May adhere to. For this reason, when the transfer belt is used, the back surface of the transfer paper is stained, and when the intermediate transfer member is used, abnormalities may occur due to toner adhering to a place other than the image forming area or toner color mixture. An image is generated. Therefore, these problems can be solved by preventing the photosensitive member 1 from coming into contact with a transfer target, for example, a transfer conveyance belt or an intermediate transfer belt, during the reverse rotation of the photosensitive member 1. As a means for preventing contact, it is desirable that the transfer medium has a mechanism for separating the photoreceptor 1 during reverse rotation of the photoreceptor 1.

  Further, as shown in FIG. 9, the photoconductor 1 is rotated in the same direction as the rotation direction at the time of image formation, that is, the normal rotation direction, and the next image forming operation is controlled to be performed from the surface of the photoconductor 1 without toner (not shown). Control means can also be provided. Thereby, the charging uniformity of the photoreceptor 1 can be ensured, and the occurrence of abnormal images can be prevented. Further, when the control means is performing the control, charging by the charging device 2, exposure by the exposure device 3, and development by the developing device 4, and an image to be output must not be created and output. However, at this time, the voltage application to the polarity control member 10, the voltage application to the electrostatic cleaning member 11, and the drive need to be performed in the same manner as in a normal image forming operation. The next image forming operation needs to be performed after the control is completed.

  Further, the rotational distance of the photosensitive member 1 when performing the control needs to be greater than the peripheral length of the photosensitive member 1 between the polarity control member 10 and the photosensitive member contact point of the charging device 2 in the normal rotation direction of the photosensitive member 1. is there. Since the toner whose polarity is not controlled cannot be output to the printed image, it is necessary to use the surface of the photoreceptor 1 after the toner whose polarity is controlled is cleaned for image formation. Therefore, in order to enter the charging process using the surface of the photoreceptor 1 after the toner has been completely cleaned, the polarity control member 10, the charging device 2, and the like in the normal rotation direction of the photoreceptor 1 before the image forming operation is started. The photosensitive member 1 needs to move a distance greater than the peripheral length of the photosensitive member between the photosensitive member contact points. As a result, the next image forming operation can be performed from the surface of the photosensitive member 1 without toner, so that the charging uniformity of the photosensitive member 1 can be ensured and the occurrence of an abnormal image can be prevented.

  At this time, the charging device 2 should not be charged until the photosensitive member 1 moves in the normal rotation direction of the photosensitive member 1 between the photosensitive member contact points of the polarity control member 10 and the charging device 2. Further, the developing device 4 must not perform development until the photosensitive member 1 moves in the normal rotation direction of the photosensitive member 1 between the photosensitive member contact points of the polarity control member 10 and the developing device 4. The polarity control member 10 applies a voltage in the normal rotation direction of the photoconductor 1 from the start of rotation in the normal rotation direction to the end of rotation in the normal rotation direction. It is necessary to align the polarity of the toner existing upstream in the normal rotation direction of the body 1. The electrostatic cleaning controller applies a voltage in the normal rotation direction of the photoconductor 1 by applying a voltage to the collection roller 12 from the start of rotation in the normal rotation direction to the end of the rotation in the same direction. It is necessary to clean the toner that is applied and driven, and exists on the upstream side of the photosensitive member 1 in the normal rotation direction of the electrostatic cleaning member 11 and is input to the electrostatic cleaning member 11. By the above control, the next print image forming operation can be performed using the surface of the photoreceptor 1 without toner.

  Next, when the timing at which the control means performs the upper control is after the end of the image forming operation as shown in FIG. 10, the timing at which the photosensitive member 1 rotates in the opposite direction to that at the time of image formation is after the end of the image forming operation. Therefore, at the start of the next image forming operation, since there is no toner remaining between the contact points of the polarity control member 10 and the electrostatic cleaning member 11 on the photoreceptor 1, an abnormal image is generated in the next printing process. There is no. Further, since the photosensitive member 1 is rotated in the reverse direction at the end of the previous image forming operation, it is possible to smoothly shift to the next image forming operation and reduce the image output waiting time of the user. Further, when rotating in the normal rotation direction at the timing, the toner remaining between the contact points of the polarity control member 10 and the electrostatic cleaning member 11 on the photoreceptor 1 is not output as a print image, Since image formation can be performed on the surface of the photoreceptor 1 without toner, abnormal images are not generated. Further, this allows the image forming apparatus to smoothly shift to the image forming operation. Further, since the photosensitive member 1 is not rotated in the reverse direction, it is not necessary to provide a reverse rotating means for the photosensitive member 1, and the control becomes easier.

  Further, when the timing at which the control means performs the control is before the start of image formation as shown in FIG. 11, when the photosensitive member 1 rotates in the reverse direction, the polarity control member on the photosensitive member 1 in the pre-printing process. The toner remaining between the contact points of the photosensitive member 10 and the electrostatic cleaning member 11 is cleaned before the start of the next image forming operation, so that no abnormal image is generated. Even when the photosensitive member 1 rotates in the normal rotation direction before the start of the next image forming operation, image formation can be performed from the surface of the photosensitive member 1 without the toner.

  When the timing at which the control means performs the control is after warm-up as shown in FIG. 12, when the photoconductor 1 rotates in the opposite direction, the polarity control member 10 on the photoconductor 1 and Since there is no toner remaining between the contact points of the photosensitive member and the electrostatic cleaning member 11, an abnormal image is not generated in the next printing process. In addition, since the photosensitive member 1 is rotated in the reverse direction after the warm-up, it is possible to smoothly shift to the next image forming operation and reduce the user's image output waiting time. Even when the photosensitive member 1 rotates in the normal rotation direction after warm-up, image formation can be performed from the surface of the photosensitive member 1 without the toner.

  Next, when the photosensitive member 1 is soft, the photosensitive member 1 is very easily worn. When the photoconductor 1 is worn, the surface roughness increases. Then, due to the minute surface roughness, the toner is caught on the surface of the photosensitive member 1 and is difficult to clean. For this reason, it is necessary to use the photoconductor 1 which is not easily worn so that the surface roughness of the photoconductor 1 does not increase with time. Therefore, the wear resistance of the surface layer of the photoreceptor 1 can be improved by dispersing and reinforcing the filler on the surface layer of the photoreceptor 1. Examples of organic fillers include fluororesin powders such as polytetrafluoroethylene, silicone resin powders, and a-carbon powders. Inorganic fillers include metal powders such as copper, tin, aluminum, and indium, tin oxide, and oxidation. Examples thereof include zinc, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, metal oxides such as tin-doped indium oxide, and inorganic materials such as potassium titanate. These fillers may be used alone or in combination of two or more. These fillers can be dispersed by using a suitable disperser in the protective layer coating solution. Moreover, it is preferable from the point of the transmittance | permeability of a protective layer that the average particle diameter of a filler is 0.5 micrometer or less, Preferably it is 0.2 micrometer or less. In the present embodiment, a plasticizer or a leveling agent may be added to the protective layer 21.

In addition, for the purpose of improving the wear resistance of the surface layer of the photoreceptor 1, a crosslinkable charge transfer material can be used. Hereinafter, a detailed description of the photoreceptor 1 having a crosslinked structure will be described. As the binder composition of the protective layer, a protective layer having a crosslinked structure is also effectively used. Regarding the formation of a cross-linked structure, a reactive monomer having a plurality of cross-linkable functional groups in one molecule is used to cause a cross-linking reaction using light or thermal energy to form a three-dimensional network structure. is there. This network structure functions as a binder resin and exhibits high wear resistance. From the viewpoint of electrical stability, printing durability, and life, it is a very effective means to use a monomer having a charge transporting ability in whole or in part as the reactive monomer. By using such a monomer, a charge transporting site is formed in the network structure, and the function as a protective layer can be sufficiently expressed. The reactive monomer having charge transporting ability includes a compound containing at least one charge transporting component and a silicon atom having a hydrolyzable substituent in the same molecule, and a charge transporting component in the same molecule. A compound containing a hydroxyl group, a compound containing a charge transporting component and a carboxyl group in the same molecule, a compound containing a charge transporting component and an epoxy group in the same molecule, a charge transporting component in the same molecule And a compound containing an isocyanate group. These charge transport materials having a reactive group may be used alone or in combination of two or more. More preferably, a reactive monomer having a triarylamine structure is effectively used as the monomer having a charge transporting ability because of high electrical and chemical stability and high carrier mobility.
In addition to this, monofunctional and bifunctional polymerizable monomers and polymerizable oligomers are used in combination for the purpose of viscosity adjustment during coating, stress relaxation of the cross-linked charge transport layer, low surface energy, and reduction of friction coefficient. be able to. As these polymerizable monomers and oligomers, known ones can be used.

  In this embodiment, the hole transporting compound is polymerized or cross-linked using heat or light. When the polymerization reaction is performed by heat, the polymerization reaction proceeds with the case where the polymerization reaction proceeds only with thermal energy. However, in order to advance the reaction efficiently at a lower temperature, it is preferable to add an initiator. In the case of polymerization by light, it is preferable to use ultraviolet light as light, but the reaction rarely proceeds only by light energy, and generally a photopolymerization initiator is used in combination. The polymerization initiator in this case mainly absorbs ultraviolet rays having a wavelength of 400 nm or less, generates active species such as radicals and ions, and starts polymerization. In the present invention, the aforementioned heat and photopolymerization initiators can be used in combination. The charge transport layer having a network structure formed in this manner has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and if it is too thick, it may cause cracks. In such a case, the protective layer may be a laminated structure, a low molecular dispersion polymer protective layer may be used for the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure may be formed on the upper layer (surface side). good.

Next, an example of the photoreceptor 1 using the above-mentioned crosslinking type protective layer is shown.
<Photoreceptor A>
Photoreceptor A was produced in the same manner as Photoreceptor 1, except that the protective layer coating solution, film thickness, and preparation conditions were changed as follows. 182 parts of methyltrimethoxysilane, 40 parts of dihydroxymethyltriphenylamine, 225 parts of 2-propanol, 106 parts of 2% acetic acid, and 1 part of aluminum trisacetylacetonate were mixed to prepare a coating solution for the protective layer. This coating solution was applied onto the charge transport layer and dried, and then heat-cured at 110 ° C. for 1 hour to form a protective layer having a thickness of 3 μm.
<Photoreceptor B>
Photoreceptor B was prepared in the same manner as Photoreceptor 1, except that the protective layer coating solution, film thickness, and preparation conditions were changed as follows. 30 parts of a hole transporting compound (Chemical Formula 1 below), acrylic monomer (Chemical Formula 2 below) and 0.6 part of a photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) are mixed with 50 parts of monochlorobenzene / 50 parts of dichloromethane. Part of the mixture was dissolved in a mixed solvent to prepare a coating material for the surface protective layer. This paint was applied on the previous charge transport layer by spray coating, and cured for 30 seconds with a light intensity of 500 mW / cm ² using a metal halide lamp to form a surface protective layer having a thickness of 5 μm.

  Further, for the purpose of improving the abrasion resistance of the surface layer of the photoreceptor 1, the conductive support is heated to 50 ° C. to 400 ° C., and a vacuum deposition method, a sputtering method, an ion plating method, thermal CVD is applied on the support. An amorphous silicon photoconductor (hereinafter, referred to as “a-Si-based photoconductor 1”) having a photoconductive layer made of a-Si can be used by a film forming method such as a CVD method, a photo CVD method, or a plasma CVD method. . Among them, a plasma CVD method, that is, a method in which a source gas is decomposed by direct current, high frequency or microwave glow discharge to form an a-Si deposited film on a support is preferably used.

  The layer structure of the amorphous silicon photoconductor is, for example, as follows. FIG. 13 is a schematic configuration diagram for explaining a layer configuration. In the electrophotographic photoreceptor 500 shown in FIG. 13A, a photoconductive layer 502 made of a-Si: H, X and having photoconductivity is provided on a support 501. A photoconductor 500 shown in FIG. 13B includes a photoconductive layer 502 made of a-Si: H, X and having photoconductivity on a support 501, and an amorphous silicon-based surface layer 503. Yes. A photoconductor 500 shown in FIG. 13C has a photoconductive layer 502 made of a-Si: H, X and having photoconductivity, an amorphous silicon-based surface layer 503, and an amorphous silicon-based material on a support 501. And a charge injection blocking layer 504. A photoconductor 500 shown in FIG. 13D is provided with a photoconductive layer 502 on a support 501. The photoconductive layer 502 includes a charge generation layer 505 made of a-Si: H, X and a charge transport layer 506, and an amorphous silicon-based surface layer 503 is provided thereon.

  The support for the photoreceptor 1 may be conductive or electrically insulating. Examples of the conductive support include metals such as Al, Cr, Mo, Au, In, Nb, Te, V, Ti, Pt, Pd, and Fe, and alloys thereof such as stainless steel. Also, at least the surface on the side where the photosensitive layer is to be formed of an electrically insulating support such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polystyrene, polyamide or other synthetic resin film or sheet, glass or ceramic. A conductively treated support can also be used. The shape of the support may be a cylindrical or plate-like or endless belt with a smooth or uneven surface, and its thickness is appropriately determined so that the desired photoreceptor 1 can be formed. When flexibility as 1 is required, it can be made as much as possible within the range in which the function as a support can be sufficiently exhibited. However, the support is usually 10 μm or more from the viewpoints of manufacturing and handling, such as mechanical strength.

  As shown in FIG. 13 (c), in the amorphous silicon photoconductor, a charge injection functioning to prevent the injection of charges from the conductive support side between the conductive support and the photoconductive layer, if necessary. It is more effective to provide a blocking layer. That is, the charge injection blocking layer has a function of blocking charge injection from the support side to the photoconductive layer side when the photosensitive layer is subjected to a charging process with a certain polarity on its free surface. When charged, it has a so-called polarity dependency that does not exhibit such a function. In order to provide such a function, the charge injection blocking layer contains a relatively large number of atoms for controlling conductivity as compared with the photoconductive layer. The layer thickness of the charge injection blocking layer is preferably from 0.1 to 5 μm, more preferably from 0.3 to 4 μm, and most preferably from 0.5 to 0.5 in view of obtaining desired electrophotographic characteristics and economic effects. It is desirable to be 3 μm.

  The photoconductive layer is formed on the undercoat layer as necessary, and the layer thickness of the photoconductive layer 502 is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic characteristics and economic effects, preferably It is desirable that the thickness is 1 to 100 μm, more preferably 20 to 50 μm, and most preferably 23 to 45 μm.

  The charge transport layer is a layer mainly having a function of transporting charges when the photoconductive layer is functionally separated. The charge transport layer includes at least silicon atoms, carbon atoms, and fluorine atoms as constituent elements, and is formed of a-SiC (H, F, O) including hydrogen atoms and oxygen atoms as required. It has conductive properties, particularly charge retention properties, charge generation properties, and charge transport properties. In the present embodiment, it is particularly preferable to contain an oxygen atom. Further, the layer thickness of the charge transport layer is appropriately determined according to desired in view of obtaining desired electrophotographic characteristics and economic effects. The charge transport layer is preferably 5 to 50 μm, more preferably 10 to 10 μm. It is desirable that the thickness is 40 μm, optimally 20 to 30 μm.

  The charge generation layer is a layer mainly having a function of generating charges when the photoconductive layer is functionally separated. This charge generation layer is composed of a-Si: H containing at least silicon atoms as components and substantially no carbon atoms and, if necessary, hydrogen atoms, and has desired photoconductive properties, particularly charge generation properties. , Has charge transport properties. The layer thickness of the charge generation layer is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic characteristics and economic effects, etc., preferably 0.5 to 15 μm, more preferably 1 to 10 μm, optimally 1 ˜5 μm.

  If necessary, the amorphous silicon photoreceptor can be further provided with a surface layer on the photoconductive layer formed on the support as described above to form an amorphous silicon-based surface layer. preferable. This surface layer has a free surface, and is provided to achieve the object of the present invention mainly in moisture resistance, continuous repeated use characteristics, electrical pressure resistance, use environment characteristics, and durability. The thickness of the surface layer is usually 0.01 to 3 μm, preferably 0.05 to 2 μm, and most preferably 0.1 to 1 μm. If the layer thickness is less than 0.01 μm, the surface layer is lost due to wear or the like during use of the photoreceptor, and if it exceeds 3 μm, electrophotographic characteristics such as an increase in residual potential are observed.

  Next, since the so-called revolver type image forming apparatus including one photosensitive member 1 and a plurality of developing devices 4 shown in FIG. 14 performs image formation of all colors with one photosensitive member 1, each color for each color is formed. Cleaning is important. If the toner remaining between the contact points of the polarity control member 10 and the electrostatic cleaning member 11 on the photoreceptor 1 at the end of the previous image forming operation is not cleaned, the next image may be a different color toner. The image is output as an image mixed with other colors in the forming operation. Therefore, by applying the present invention, it is possible to prevent the occurrence of a mixed color abnormal image.

  Further, in the so-called tandem image forming apparatus including a plurality of photoconductors and a plurality of developing units as shown in FIG. 15, the reverse transfer toner to the photoconductor is remarkably generated. Therefore, it is necessary to clean the reverse transfer toner as well. is there. This reverse transfer toner also has a different color unless the toner remaining between the contact points of the polarity control member 10 and the electrostatic cleaning member 11 on the photoreceptor 1 at the end of the previous image forming operation is cleaned. Even with toner, image formation is performed in the next image forming operation by mixing with other colors. Therefore, by applying the present invention, it is possible to prevent the occurrence of a mixed color abnormal image.

  Further, when the configuration as shown in FIG. 16 is adopted, if all the toner remaining between the transfer conveyance belt contact points of the polarity control member 10 and the electrostatic cleaning member 11 on the transfer conveyance belt is not cleaned, the transfer is performed. When the paper is transported, toner adheres to the back surface of the transfer paper, causing a problem of back surface contamination. Therefore, by rotating the transfer / conveying belt 35 as a member to be cleaned by a predetermined distance at a predetermined timing, it is possible to prevent the back surface of the transfer paper from being stained for the same reason as the photosensitive member 1.

  Further, when the intermediate transfer method is used to transfer the toner image onto the transfer paper as shown in FIG. 17, the intermediate transfer belt contact point between the polarity control member 10 and the electrostatic cleaning member 11 on the intermediate transfer belt 36 is used. Unless all the remaining toner is cleaned, toners of different colors are mixed and an abnormal image is generated in the next image forming operation. Therefore, by rotating the intermediate transfer belt 36 as a member to be cleaned by a predetermined distance at a predetermined timing, it is possible to prevent the occurrence of an abnormal image for the same reason as the photosensitive member 1.

  In order to obtain a good image, by applying the present invention to an image forming apparatus using toner having a shape factor SF1 of 100 to 150, a spherical toner having a toner shape factor SF1 of 100 to 150 can be obtained. Also in the used image forming apparatus, the toner remaining between the polarity control member 10 and the electrostatic cleaning member 11 can be cleaned, so that no abnormal image is generated. In addition, by applying the present invention, spherical toner having a high degree of circularity can be used, and high image quality can be achieved. In particular, since the toner has a shape factor SF1 of 100 to 150, such as a toner with a high degree of circularity (spherical toner), cleaning becomes difficult with other means, and thus the present invention is effective.

  Next, in order to confirm the effectiveness of the present invention, Experiment 1, Experiment 2, Experiment 3, and Experiment 4 shown below were performed.

<Experiment 1>
The toner charge amount after development and transfer was measured at room temperature and humidity.
<Experiment>
The conditions are shown below.
・ Experimental equipment: Imagio neo C600
Experimental method: The toner charge amount distribution after development and before transfer was measured.
・ Measurement color: Black ・ Image mode: Solid ・ Measurement device: E-Spart Analyzer made by Hosokawa Micron
・ Environment: Normal temperature and humidity <Experimental results>
The experimental results are shown in FIG. From this result, it can be seen that the developed toner has a negative charge and a sharp charge amount distribution, whereas the toner after transfer has a wide charge amount distribution in the positive and negative directions centering on zero.

<Experiment 2>
The toner charge amount after development and after transfer was measured at high temperature and high humidity and low temperature and low humidity.
<Experiment>
The conditions are shown below.
・ Experimental equipment: Imagio neo C600
Experimental method: The toner charge amount distribution after development and before transfer was measured.
・ Measurement color: Black ・ Image mode: Solid ・ Measurement device: E-Spart Analyzer made by Hosokawa Micron
・ Environment: High temperature and high humidity, low temperature and low humidity <Experimental results>
The experimental results are shown in FIG. 19, FIG. 20, and FIG. In FIG. 19, the toner charge amount distribution after development at normal temperature and humidity is also shown for reference. From FIG. 19, it can be seen that the toner polarity after development is all negative in polarity regardless of environmental fluctuations, and the distribution becomes closer to 0 as the temperature becomes higher. From FIG. 20, it can be seen that, at high temperature and high humidity, the transfer residual toner has a wide charge amount distribution centering on positive polarity. From FIG. 21, it can be seen that, at low temperature and low humidity, the transfer residual toner has a wide charge amount distribution centering on the negative polarity.

<Experiment 3>
From the above experiment, it became clear that the toner after development and the toner characteristics after transfer differ depending on the environment. Therefore, an experiment was conducted to determine whether the polarity of the untransferred toner can be really changed by using the polarity control member 10 aimed at controlling the polarity. Here, when it is aimed to control the charge amount of the toner to the negative polarity by applying a negative voltage to the polarity control member 10, the transfer residual toner is the most positive in Experiment 2 and the polarity control is performed. Seems to be difficult. Therefore, an experiment was performed at high temperature and high humidity as an experimental environment, and the effect of the polarity control member 10 was confirmed.
<Experiment>
The conditions are shown below.
Experimental apparatus: The experimental apparatus shown in FIG. 22 was used.
Experimental method: A certain amount of toner is developed on the entire surface of the photoreceptor 1, the developed toner is charged positively by the corona charging device 16, a negative voltage is applied to the polarity control member 10, and the polarity control member The toner charge amount distribution after 10 passes was measured.
・ Measurement color: Black ・ Image mode: Solid ・ Measurement device: E-Spart Analyzer made by Hosokawa Micron
・ Environment: High temperature and high humidity <Experimental results>
The experimental results are shown in FIG.
From this result, it is understood that the polarity control of the toner is possible even with the transfer residual toner at the high temperature and high humidity which seems to be the most difficult to control the polarity. Therefore, it became clear that the polarity of the toner can be controlled even at low temperature and low humidity and at normal temperature and humidity.

感光体１逆転制御を用いない場合、２枚目出力画像先端にうっすらとトナーが付いており、出力画像が異常と判断されることが確認できた。一方、逆転制御を用いた場合、２枚目出力画像にはトナーは付着しておらず、異常画像とならないことが確認できた。この結果から、感光体１逆転制御を加えることにより、画像品質の劣化を防止することができることが確認できた。 <Experiment 4>
Here, in order to confirm the effect of rotating the photosensitive member 1 in the reverse direction, the image forming operation was performed with a time interval between the image forming operations with and without the photosensitive member 1 reverse control. Then, by judging the image quality of the output image, it was judged whether or not the present invention is effective.
<Experiment>
The conditions are shown below.
Experimental apparatus: Imagio neo C600 modified so that the photosensitive member 1 can rotate in the reverse direction.
Reverse rotation distance: the circumference of the photoreceptor between the contact points of the polarity control member 10 and the electrostatic cleaning member 11.
・ Reverse rotation timing: After the first sheet image forming operation is completed. ・ Experiment method: A solid image is output on the first sheet. Next, after leaving for 1 hour, a blank image is output as the second sheet.
Measurement item: Image quality of the output image of the second sheet shown in FIG. 24 in the head portion 20 mm area which is the image quality evaluation area 17 (remaining between the contact points of the photosensitive member between the polarity control member 10 and the electrostatic cleaning member 11 Second sheet depending on the toner used).
・ Measurement color: Black ・ Environment: Normal temperature and humidity <Experimental result>
Here, a case where the output image was determined to be abnormal was determined as x, and a case where it was determined that there was no abnormality in the output image was determined as ◯. The experimental results are shown in Table 1.

When the photoreceptor 1 reverse rotation control was not used, it was confirmed that the toner was slightly attached to the leading edge of the second sheet output image, and the output image was judged to be abnormal. On the other hand, when reverse rotation control was used, it was confirmed that no toner was adhered to the second output image and no abnormal image was formed. From this result, it was confirmed that image quality deterioration can be prevented by adding the photoreceptor 1 reverse rotation control.

As described above , according to the present embodiment, the photosensitive member 1 that can rotate forward and backward in the circumferential direction and the electrostatic cleaning member that contacts the surface of the photosensitive member 1 and electrostatically removes the toner attached to the photosensitive member 1. 11, a polarity control member 10 for controlling the polarity of the toner, provided upstream of the electrostatic cleaning member 11 in the normal direction of the photosensitive member 1, and upstream of the polarity control member 10 in the rotational direction of the photosensitive member 1. In a printer provided with a charging device 2 for charging the photoconductor 1 provided upstream of the electrocleaning member 11 in the rotation direction of the photoconductor 1, the photoconductor 1 is connected to the polarity control member 10 until the next image formation. Control means is provided for controlling a distance longer than the circumferential length of the photosensitive member between contact points of the photosensitive member with the electrostatic cleaning member 11 so as to rotate in a direction opposite to the normal rotational direction. As a result, the photoconductor 1 rotates in the direction opposite to the normal rotation direction during image formation, and the toner can be moved again to the upstream side of the polarity control member 10 in the normal photoconductor 1 rotation direction. Therefore, at the time of the next image formation, the toner can be charged by passing through the polar means, so that the toner can be cleaned by the electrostatic cleaning member 11 . Also, the upper Symbol polarity control member 10, when the control means performs the control, and is configured so as to be separated from the photosensitive member 1. As a result, the polarity control member 10 is separated from the photoconductor 1 when the photoconductor 1 rotates in the opposite direction to that during image formation, so that the toner can be prevented from being blocked by the polarity control member 10.
Further, in this embodiment, when the corona charging device 16 is used, the surface of the photoconductor 1 is excessively charged by the rotation distance obtained by rotating the photoconductor 1 in the reverse direction. Sometimes the toner development amount becomes non-uniform in that region. Further, when a contact or contacted roller charging unit is used, the surface of the photoreceptor 1 may be scraped by a discharge that occurs when a voltage is applied to cause the power outage of the surface of the photoreceptor 1. Therefore, when the control means performs the control, the charging device 2 does not charge the surface of the photoreceptor 1. As a result, even when the next image is formed, a uniform toner image can be formed on the photoreceptor 1 and wear of the photoreceptor 1 can be suppressed.
Further, according to the present embodiment, the circumference of the elephant carrier between the contact points of the polarity control member 10 and the electrostatic cleaning member 11 is A, and the photosensitive member between the charging device 2 and the developing device 4. When the circumference of the elephant carrier between the contact points is B, A <B is satisfied. When A ≧ B, when the photoreceptor 1 is rotated in the reverse direction by the circumference of the photoreceptor between the contact points of the polarity control member 10 and the electrostatic cleaning member 11, the photoreceptor 1 The contact point between the photosensitive member 1 and the developing device 4 immediately before the rotation in the reverse direction is returned to the upstream side of the charging device 2 in the rotational direction of the photosensitive member 1. Since toner may adhere to the surface of the photosensitive member 1 when passing through the contact point with the developing device 4, the photosensitive member 1 rotates more than the charging device 2 when the photosensitive member 1 rotates in the reverse direction. The surface of the photoreceptor 1 to which the toner is attached returns to the upstream side in the direction. When the next image forming operation is started in this state, the charging device 2 charges the surface of the photoreceptor 1 to which the toner adheres, and the surface of the photoreceptor 1 cannot be uniformly charged. Therefore, by satisfying A <B, the charging device 2 can always charge the toner-free surface of the photoreceptor 1, so that the surface of the photoreceptor 1 can be uniformly charged.
Further, according to the present embodiment, the image forming apparatus includes the transfer device 5 that transfers the toner image on the photoconductor 1 to the transfer target, and the photoconductor 1 is subjected to the control when the control unit performs the control. It is configured not to contact the transfer body. As a result, for example, when the transfer target is a transfer conveyance belt or an intermediate transfer belt, the transfer paper belt can be prevented from becoming dirty on the back side of the transfer paper. When the intermediate transfer belt is used, a place other than the image forming area can be suppressed. It is possible to suppress the occurrence of abnormal images due to toner adhesion or toner color mixture.
Further, according to the present embodiment, the developing device 4 does not supply the developer onto the photoreceptor 1 when the control unit performs the control. As a result, toner is not consumed when it is not related to image formation, and toner consumption can be reduced.
In addition, according to the present embodiment, the photosensitive member 1 having a protective layer containing a filler (particulate matter) is used. Thereby, the abrasion resistance of the surface of the photoreceptor 1 can be improved.
Further, according to this embodiment, the photoreceptor 1 has characteristics of an organic photoreceptor having a surface layer reinforced with a filler, an organic photoreceptor using a cross-linked charge transport material, or both. Even in the case of the organic photoreceptor having the above, the abrasion resistance of the surface layer of the photoreceptor 1 can be improved.
In addition, according to the present embodiment, even if the photosensitive member 1 having a surface layer made of amorphous silicon is used, the wear resistance of the surface layer of the photosensitive member 1 can be improved.
Further, according to the present embodiment, a so-called revolver type image forming apparatus that forms a multicolor image on a single photoreceptor 1 by a developing device 4 including a plurality of developing devices may be used as the image forming apparatus. The effects described above can be obtained.
Further, according to the present embodiment, the image forming apparatus includes a plurality of image forming units each including one photoconductor 1 and one developing device, and the toner images formed by the plurality of image forming units are superposed. Even if a so-called tandem type image forming apparatus that forms a multicolor image is used, the above-described effects can be obtained.
Further, according to the present embodiment, at least one means selected from the charging device 2, the developing device 4, the polarity control member 10, and the electrostatic cleaning member 11 and the photoreceptor 1 are integrally supported. In addition, by providing a process cartridge that can be attached to and detached from the image forming apparatus main body, the gaps between the respective means can be assembled with high accuracy, and the replacement work of consumables is not only simplified, Generation of abnormal images due to gap fluctuations and unexpected device troubles can be prevented.
According to the present embodiment, the control unit performs the control after the image forming operation is completed. As a result, when the next image forming operation is started, image formation can be started from the surface of the photoconductor 1 without the toner on the photoconductor 1 or without the toner, so that an abnormal image is generated during the next image formation. Can be suppressed.
According to the present embodiment, the control means performs the control before starting the image forming operation. As a result, the toner remaining on the photoreceptor 1 during the previous image forming operation can be cleaned before the start of the next image forming operation, or an image can be formed from the surface of the photoreceptor 1 without the toner. Therefore, it is possible to suppress the occurrence of an abnormal image.
According to the present embodiment, the control means performs the control after warming up. Thereby, the image formation can be started from the surface of the photoconductor 1 without the toner on the photoconductor 1 after the warm-up or without the toner, so that the occurrence of an abnormal image during the image formation after the warm-up is suppressed. be able to.
In addition, according to the present embodiment, even when the toner has a shape factor SF-1 in the range of 100 to 150, the spherical toner can be cleaned, so that an abnormal image is generated. High-quality image output can be performed without any problem.
Further, according to the present embodiment, even if the member to be cleaned is the intermediate transfer belt 36 that is an intermediate transfer unit, the same effect as that of the photosensitive member 1 can be obtained.
In addition, according to the present embodiment, even if the object to be cleaned is the transfer conveyance belt 35 which is a transfer conveyance body, the same effect as that of the photoconductor 1 can be obtained. It is possible to suppress contamination with toner.

FIG. 3 is a schematic configuration diagram of a toner cleaning technology to which the present invention is applied and in which a photoreceptor rotates in reverse. FIG. 2 is a schematic configuration diagram of a toner cleaning technique that is taken up as a problem of the present invention. 1 is a schematic configuration diagram of an entire image forming apparatus according to an exemplary embodiment. 1 is a schematic configuration diagram of a process cartridge to which the present invention is applied. The dispersion state of conductive fine particles in a brush as an electrostatic cleaning member used in an image forming apparatus to which the present invention is applied. Fully dispersed brush. The dispersion state of conductive fine particles in a brush as an electrostatic cleaning member used in an image forming apparatus to which the present invention is applied. Brush dispersed only at the outer periphery. The dispersion state of conductive fine particles in a brush as an electrostatic cleaning member used in an image forming apparatus to which the present invention is applied. Brush dispersed only inside. 6 is a flowchart showing timing for separating the polarity control member from the photosensitive member 1 in the image forming apparatus to which the present invention is applied. FIG. 3 is a schematic configuration diagram of a toner cleaning technique to which the present invention is applied and in which a photoreceptor rotates forward. 6 is a flowchart showing the timing at which a photoreceptor rotates in an image forming apparatus to which the present invention is applied. 6 is a flowchart showing the timing at which a photoreceptor rotates in an image forming apparatus to which the present invention is applied. 6 is a flowchart showing the timing at which a photoreceptor rotates in an image forming apparatus to which the present invention is applied. Explanatory drawing of the layer structure of an amorphous silicon photoreceptor. 1 is a schematic configuration diagram when the present invention is applied to a revolver type image forming apparatus. 1 is a schematic configuration diagram when the present invention is applied to a tandem image forming apparatus. FIG. 2 is a schematic configuration diagram when the present invention is applied to a transfer conveyance belt. FIG. 2 is a schematic configuration diagram when the present invention is applied to an intermediate transfer belt. Experimental results of toner charge amount distribution after development and transfer at normal temperature and humidity. Experimental results of toner charge distribution after development at high temperature and high humidity and low temperature and low humidity. Experimental results of toner charge distribution after development and after transfer at high temperature and high humidity. Experimental results of toner charge distribution after development and after transfer at low temperature and low humidity. The experimental apparatus schematic diagram for confirmation of the feasibility of a polarity control means. The experimental result of the transfer residual toner and the toner charge amount distribution after passing through the polarity control means at high temperature and high humidity. Output image evaluation area of Experiment 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging apparatus 3 Exposure apparatus 4 Developing apparatus 5 Transfer apparatus 10 Polarity control member 11 Electrostatic cleaning member 35 Transfer conveyance belt 36 Intermediate transfer belt

Claims (18)

An object to be cleaned that can rotate forward and backward in the circumferential direction;
Electrostatic cleaning means for electrostatically removing the toner adhering to the object to be cleaned in contact with the surface of the object to be cleaned;
A polarity control means for controlling the polarity of the toner, provided upstream of the electrostatic cleaning means in the normal rotation direction of the member to be cleaned;
An image provided with a charging means for charging the object to be cleaned provided upstream of the object to be cleaned in the normal rotation direction of the polarity control means and upstream of the object to be cleaned in the normal rotation direction of the electrostatic cleaning means; In the forming device,
Before the next image formation, the object to be cleaned is longer than the circumference of the object to be cleaned between contact points of the object to be cleaned between the polarity control unit and the electrostatic cleaning unit. a control means for controlling to rotate the,
The polarity control unit, an image forming apparatus to which the control means is characterized in that when performing the control, and is configured so as to be separated from該被cleaning member. The image forming apparatus according to claim 1 .
The image forming apparatus, wherein the charging unit does not charge the surface of the object to be cleaned when the control unit performs the control. The image forming apparatus according to claim 1 or 2,
An image carrier for carrying an image;
Developing means for developing an image on the image carrier with toner to form a toner image;
The image forming apparatus, wherein the member to be cleaned is the image carrier. The image forming apparatus according to claim 1 or 2 ,
An image carrier for carrying an image;
Developing means for developing an image on the image carrier with toner to form a toner image;
The object to be cleaned is the image carrier, and the circumference of the elephant carrier between the contact points of the polarity control means and the electrostatic cleaning means is A, and the image of the charging means and the developing means An image forming apparatus characterized by satisfying the relationship of A <B, where B is the circumference of the elephant carrier between the contact points of the carrier. The image forming apparatus according to claim 3 or 4 ,
A transfer means for transferring the toner image on the image carrier to the transfer target;
The image forming apparatus, wherein the image bearing member is configured not to contact the transferred member when the control means performs the control. The image forming apparatus according to claim 3, 4 or 5 .
The image forming apparatus, wherein the developing unit does not supply the developer onto the image carrier when the control unit performs the control. The image forming apparatus according to claim 3, 4, 5 or 6 .
An image forming apparatus comprising a protective layer containing a filler (particulate matter) as the image carrier. The image forming apparatus according to claim 3, 4, 5 or 6 .
The image carrier is an organic photoreceptor having a surface layer reinforced with a filler, an organic photoreceptor using a cross-linked charge transport material, or an organic photoreceptor having both characteristics. An image forming apparatus. The image forming apparatus according to claim 3, 4, 5 or 6 .
An image forming apparatus comprising the use of those surface layer composed of amorphous silicon as the image carrier is formed. The image forming apparatus according to claim 3, 4, 5, 6, 7, 8, or 9 .
An image forming apparatus, wherein a multicolor image is formed on a single image carrier by developing means comprising a plurality of developing units. The image forming apparatus according to claim 3, 4, 5, 6, 7, 8, or 9 .
Image forming characterized in that it has a plurality of image forming units consisting of one image carrier and one developing device, and forms a multicolor image by superimposing toner images formed by the plurality of image forming units apparatus. The image forming apparatus according to claim 3, 4, 5, 6, 7, 8, or 9 .
At least one means selected from the charging means, the developing means, the polarity control means, and the electrostatic cleaning means, and the image carrier are integrally supported and detachable from the image forming apparatus main body. An image forming apparatus comprising a process cartridge. The image forming apparatus according to claim 1 or 2,
An image carrier for carrying an image;
Developing means for developing an image on the image carrier with toner and forming a toner image;
An intermediate transfer member carrying a toner image transferred from the image carrier;
First transfer means for transferring a toner image from the image carrier to the intermediate transfer member;
Second transfer means for transferring the toner image from the intermediate transfer member to the recording member,
The image forming apparatus, wherein the member to be cleaned is the intermediate transfer member. The image forming apparatus according to claim 1 or 2,
An image carrier for carrying an image;
Developing means for developing an image on the image carrier with toner and forming a toner image;
A transfer carrier that conveys a recording member onto which the toner image on the image carrier is transferred to a transfer position facing the surface of the image carrier;
The image forming apparatus, wherein the member to be cleaned is the transfer carrier. The image forming apparatus according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14.
The image forming apparatus according to claim 1, wherein the control unit performs the control after the image forming operation is completed. The image forming apparatus according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14.
It said control means, the image forming apparatus, wherein the der Turkey performs the control before the image forming operation start. The image forming apparatus according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14.
The image forming apparatus according to claim 1, wherein the control means performs the control after warm-up. The image forming apparatus according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17 .
A toner having a shape factor SF-1 in the range of 100 to 150 is used as the toner.

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