JP2017054106A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the duration of use of a developing device by efficiently removing an attachment attached to a developer carrier.SOLUTION: A developer carrier rotates in a first direction of rotation, and a stirring member rotates in a second direction of rotation that is the direction opposite to the first direction of rotation. In a contact area where the stirring member is in contact with the developer carrier, the moving speed of the developer carrier is faster than the moving speed of the stirring member.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a developing device, a process cartridge, and an image forming apparatus.

  Here, the process cartridge means a cartridge having at least an image carrier. In many cases, the charging unit, the developing unit, the cleaning unit, and the image carrier are integrally formed as a cartridge, and the cartridge can be attached to and detached from the main body of the image forming apparatus.

  Further, the developing device means a device having at least a developer carrying member. In many cases, the developer carrying member, the developing frame that supports the developer carrying member, and the parts related thereto are integrated and detachable from the apparatus main body of the image forming apparatus.

  In an electrophotographic image forming apparatus using an electrophotographic method such as a laser beam printer or a copying machine, toner is used as a powdery developer. The toner is accommodated in the developing container, conveyed to the toner carrier by a toner conveying means such as a stirring sheet, and held on the toner carrier. Then, a predetermined charge is applied by a developing blade as a toner layer thickness regulating member, and the toner moves to an electrostatic latent image forming unit on an image carrier that carries an image, and electrostatic latent image on a photoconductor that is an image carrier. Visualize the image. Thereafter, the visible image is transferred to a transfer material such as paper by a transfer means and fixed by a fixing device. The toner remaining on the image carrier without being transferred to the transfer material is peeled off from the image carrier by the cleaning device in contact with the image carrier and sent to the cleaning container. After a series of these image forming processes, the user can obtain a desired image.

  As one development method, a jumping development method is known in which a latent image on an image carrier is developed while the developer carrier of the image forming apparatus is held in contact with the image carrier. Here, an example of a developing device employing the jumping development method will be described.

  In the developing device using the jumping developing method, the toner accommodated in the developing container is conveyed by a stirring sheet or the like and held on a developing sleeve as a developer carrying member. As the developing sleeve rotates, the toner as the one-component developer held on the developing sleeve is conveyed toward the developing area facing the photoconductor as the image carrier. During the conveyance, the toner is regulated by a blade in contact with the developing sleeve, and is applied in a thin layer on the developing sleeve. In the developing region, the developing sleeve and the photosensitive member are held with a gap of 50 to 500 μm. Then, by applying a developing bias in which alternating current is superimposed on direct current to the developing sleeve, the toner coated in a thin layer on the developing sleeve flies to and adheres to the electrostatic latent image on the photosensitive member, so that the latent image Is visualized as a toner image.

  As a means for achieving such a longer life of the developing device (longer use period), there is a method in which a stirring sheet as a stirring member is rotated in the same direction as the rotation direction of the developer carrier and brought into contact therewith. Known (Patent Document 1). The construction of this developing device is shown in FIG. By bringing the stirring sheet, which is a stirring member, into contact with the developer carrying member, it is made difficult for the developer carrying member to move around the developing sleeve and to deposit on the developer carrying member due to foreign matters such as paper dust and other fine powders. As a result, deposition of deposits on the surface of the developing sleeve is reduced, and thus a technique for extending the life of the developing device by extending the period until the image is affected is disclosed.

JP 2001-117369 A

  However, with the configuration as in Patent Document 1, the deposits on the developer carrier cannot be sufficiently reduced. For example, the area where the toner is peeled off from the developer carrying member may overlap with the area where the toner is conveyed on the developer carrying member. In this case, since the toner is in a dense state (region C surrounded by a dotted line in FIG. 7), the adhesion of the adhering material such as the accompanying toner cannot be sufficiently reduced, and the life of the developing device is long. (Prolonged use period) is difficult to achieve.

The developing device of the present invention is
A developer carrying body for carrying the developer and forming an image by rotating the developer to adhere to the image carrying body; and
An agitating member for agitating the developer, comprising: a rotating member that rotates; and a flexible sheet member that is attached to the rotating member, wherein a free end of the sheet member is within an image forming region of the developer carrier. A stirring member configured to be in contact with the surface of
The developer carrier rotates in a first rotation direction;
The stirring member rotates in a second rotation direction that is opposite to the first rotation direction;
The moving speed of the developer carrying member is higher than the moving speed of the stirring member in a contact region where the stirring member and the developing carrier are in contact with each other.

In addition, another developing device of the present invention is
A developer carrier that carries a developer and attaches the developer to the image carrier by rotating to form an image, and the image formed on the image carrier is transferred to a recording medium A developer carrier for recovering the developer remaining on the image carrier;
An agitating member for agitating the developer by rotating, the agitating member configured to come into contact with a surface in an image forming region of the developer carrying member when rotating,
The developer carrier rotates in a first rotation direction;
The stirring member rotates in a second rotation direction that is opposite to the first rotation direction;
The moving speed of the developer carrying member is higher than the moving speed of the stirring member in a contact region where the stirring member and the developing carrier are in contact with each other.

  The present invention also provides a process cartridge and an image forming apparatus.

  As described above, it is possible to lengthen the use period of the developing device by efficiently removing the deposits adhering to the developer carrier.

Schematic cross-sectional view of the developing device according to the present invention described in Example 1 Schematic showing the positional relationship between the developing sleeve and the stirring member as seen from the X direction in FIG. 1 is a schematic sectional view of an image forming apparatus according to the present invention described in Embodiment 1. FIG. Schematic which shows the motion which the image development sleeve and stirring sheet of Example 1 rotate in the same direction when it sees from a contact part. Conceptual diagram showing a driving configuration of the developing sleeve and the agitating member described in the first embodiment. Schematic sectional view of an image forming apparatus using the cleanerless system described in Example 2 Schematic diagram showing the movement of the stirring sheet in the opposite direction to the developing sleeve for explaining the conventional example

Example 1
Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings. The examples described below illustrate the present invention by way of example, and the dimensions, materials, shapes, relative arrangements, etc. of the components described below are not particularly specified unless otherwise specified. However, the scope of the present invention is not limited thereto.

  First, the image forming process and the configuration of the image forming apparatus will be described with reference to FIG.

  FIG. 3 is a schematic configuration diagram of an image forming apparatus according to the present invention. This image forming apparatus is a monochrome laser printer using an electrophotographic process.

<Image formation process>
When the print signal is input to the controller of the image forming main body, the image forming operation is started. Each drive unit starts moving at a predetermined timing, and a voltage is applied.

  The photosensitive drum 1 that is a rotationally driven image carrier is uniformly charged by a charging roller 2 that is a charging member. The uniformly charged photosensitive drum 1 is exposed by a laser beam L from a scanner unit 4 as an exposure unit, and an electrostatic latent image (or electrostatic image) is formed on the surface thereof. Thereafter, the electrostatic latent image is visualized as a developer image by being supplied with a developer by a developing sleeve 31 which is a developer carrying member.

  On the other hand, the recording medium P is separated and fed from the recording medium container 70 by the recording medium supply unit 71, and in synchronization with the timing of forming the developer image on the photosensitive drum 1, the transfer roller 5 serving as transfer means and the photosensitive drum. The recording medium P is sent out to a portion (transfer portion) opposite to 1.

  Thus, the visualized developer image on the photosensitive drum 1 is transferred to the recording medium P by the action of the transfer roller 5. The recording medium P to which the developer image has been transferred is conveyed to the fixing unit 6. Here, the unfixed toner image on the recording medium P is fixed to the recording medium P by heat and pressure. Thereafter, the recording medium P is discharged out of the image forming apparatus main body by a discharge roller or the like. On the other hand, the untransferred developer remaining on the photosensitive drum 1 after the developer image transfer is removed by the cleaning device 8, and the next image forming process is performed.

<Description of developing device>
In this embodiment, a non-contact developing method (jumping developing method) is adopted, and the configuration of the developing device 3 shown in FIG. 3 is used. A more detailed configuration is shown in FIGS. The developing device of this embodiment is configured to be detachable from the main body of the image forming apparatus.

  FIG. 1 shows the position (posture during use) of the developing device when the developing device is mounted on the main body of the image forming apparatus. FIG. 2 shows an arrangement relationship between the developing sleeve and the stirring member as viewed from the X direction in FIG. Specifically, FIG. 2 shows a contact state when a free end 34 a 1 of a stirring member described later contacts the outer peripheral surface of the developing sleeve 31. 2 is the longitudinal direction of the developing sleeve.

  As shown in FIG. 1, at the mounting position, the lowermost portion of the developer carrier is located above the bottom of the developer storage chamber (toner container 300) that stores the developer. In other words, the bottom of the developer storage chamber is at a lower position than the lowermost part of the developer carrier. It has a so-called pumping configuration.

  In this embodiment, a magnetic toner as a magnetic developer is used as the developer. However, the developer is not limited to this, and may be a two-component composed of a carrier and a toner, or may be non-magnetic depending on the configuration.

  The developing device includes a developing container 301 (developing chamber) and a toner container 300 (developer housing chamber) that stores toner. The developing container 301 includes a developing sleeve 31 that is a developer carrying member and a developing blade 33 that is a layer thickness regulating member that regulates the layer thickness of the developer. The toner container 300 includes a stirring member 34, and the developing container 301 and the toner container 300 communicate with each other via a developing opening A (opening 302). The developing container 301 and the toner container 300 are constituted by two frames (36a, 36b) of a first frame 36a and a second frame 36b, and the developing opening A is provided in the first frame 36a.

  The developing sleeve 31 is obtained by coating a base tube with a paint in which carbon is dispersed, and is non-magnetic. The base tube is made of aluminum, stainless steel, or the like.

  The surface of the developing sleeve 31 has a roughness due to the paint coating, and the roughness contributes to the toner transportability of the developing sleeve 31. Further, the developing sleeve 31 is rotatably supported by a bearing (not shown), and rotates in the direction R1 in FIG. The developing sleeve 31 is connected to a power source that can superimpose an AC bias on a DC bias, and a latent image on the photosensitive drum 1 is visualized as a toner image by applying a bias by the power source. The developing sleeve 31 is supported to face the photosensitive drum 1 with a predetermined developing interval. A developing blade 33, which is a toner layer thickness regulating member that regulates the toner layer thickness (application amount) on the developing sleeve 31, imparts an appropriate tribo to the toner by frictional charging. The developing blade 33 is a urethane rubber blade. The toner layer thickness on the developing sleeve 31 is set to be thinner than the minimum gap between the photosensitive drum 1 and the developing sleeve 31. The toner is a negative toner as a magnetic one-component developer (one-component developer).

  The developing sleeve 31 includes a magnet roller 32, which is a magnetic material, and is fixedly disposed. The magnet roller 32 has magnetic poles in four directions as shown in the figure. Of the four magnetic poles, the S2 pole is necessary to keep the toner that causes fogging on the developing sleeve 31 when the toner flies onto the photosensitive drum 1 and is developed. The S1 pole is disposed on the opposite side of the S2 pole, and the toner in the developing container 301 is attracted to the developing sleeve 31. Both the N1 and N2 poles contribute to the conveyance of toner coated on the developing sleeve 31 and the provision of tribo. In this embodiment, a magnet roller having a four-pole configuration is used. However, the number of poles is not limited to four if there is a pole that performs the above function.

  Thus, in this embodiment, the developer carrying member (developing sleeve 31) carries the developer and rotates to attach the developer to the image carrying member (developer image) to form an image. It is a configuration.

  Further, a toner blowing prevention sheet 35 is provided inside the developing container corresponding to the lower portion of the developing sleeve 31 to prevent toner leakage from the lower portion of the developing sleeve 31.

  The stirring member fixes the stirring sheet 34a which is a flexible sheet member to the stirring shaft portion 34b which is a rotating member. Specifically, one side of the stirring sheet 34a is attached to the stirring shaft portion, and the other side is a free end 34a1. The center of the stirring shaft portion 34b becomes the rotation center 34c, and becomes the axis of the stirring shaft.

  The agitating sheet 34 a comes into contact with the bottom of the toner container with an intrusion amount and loosens the toner contained in the toner container 300. Further, when the stirring sheet 34a rotates while rubbing the bottom of the toner container, the toner is conveyed from the toner container 300 to the developing container 301.

  The agitating sheet 34a that has conveyed the toner rotates in the direction R2 in FIG.

  After the contact, the toner further rotates to bring a part of the toner in the developing chamber back to the toner chamber, and the circulation of the toner in the toner chamber and the developing chamber is activated.

  Thus, the stirring member stirs the developer by rotating. The agitating member is configured to come into contact with the surface (outer peripheral surface) in the image forming area (shown in FIG. 2) of the developer carrying member (developing sleeve 31) when rotating. The image forming area on the developer carrier is an area on the developer carrier corresponding to the area of the electrostatic latent image formed on the image carrier.

  Except for a specific stop position, when the stirring member is not rotating, the stirring sheet and the surface of the developer carrying member (developing sleeve 31) may not come into contact with each other. When the stirring member starts rotating, the stirring sheet can come into contact with the surface of the developing sleeve.

  The agitating member 34 is disposed in the developer accommodating chamber, and the agitating sheet 34a has a length that allows contact with the bottom of the developer accommodating chamber. As a result, the stirring member can easily stir the developer near the bottom of the stirred developer storage chamber.

<Toner fusion>
The toner charge amount and layer thickness on the developing sleeve 31 depend on the state of the developing sleeve surface and the like. Therefore, in order to maintain a uniform image quality throughout the life of the cartridge, it is necessary to reduce the change in the developing sleeve surface state throughout the life of the cartridge. An example of a change in the developing sleeve surface state is toner fusion, which is a factor that determines the life of the cartridge. The process for forming the toner fusion of the developing sleeve is as described below.

  When the cartridge is used under severe conditions such as when the number of printed sheets per day is excessively large or when continuous printing is excessively performed, the temperature of the toner rises together with the temperature inside the cartridge. In particular, during severe use in a high temperature and high humidity environment, when the temperature of the toner is raised to a temperature close to the glass transition point, the toner becomes soft and easily deteriorated. In this state, when the printing on the developing sleeve consumes less toner, so-called low printing rate printing is repeated, toner circulation on the developing sleeve does not occur actively, and the toner is repeatedly regulated by the developing blade. As a result, toner fusion occurs in which the toner adheres to the surface of the developing sleeve.

  When the toner is fused to the developing sleeve, the tribo is lowered due to the change in the sleeve surface layer, the toner conveyance amount on the sleeve is changed (change) due to the change in the roughness of the sleeve, and it becomes difficult to form an appropriate image. It becomes necessary to replace the cartridge. If it becomes like this, the use period of a cartridge cannot be extended enough.

<Abutting configuration of stirring sheet and developing sleeve>
Next, a contact configuration between the stirring sheet and the developing sleeve will be described.

  In this embodiment, in order to effectively remove the toner on the developing sleeve, the surfaces of the stirring sheet and the developing sleeve are in contact with each other while rotating in the forward direction as shown in FIG. Further, the peripheral speed (moving speed) of the developing sleeve is faster than the peripheral speed (moving speed) of the stirring sheet.

  Specifically, the developer carrier (developing sleeve 31) rotates in the first rotation direction (R1), and the stirring member 34 rotates in the second rotation direction (R2) that is opposite to the first rotation direction. To do. Further, in the contact region where the stirring member and the developer carrying member are in contact, the moving speed (linear velocity) of the contact portion (31a) of the developer carrying member is greater than the moving speed (linear velocity) of the contacting portion (34d) of the stirring member. Is set too fast.

(1) Rotation direction of stirring sheet and developing sleeve By adopting the configuration as described above, the toner on the developing sleeve is scraped off each time the stirring sheet contacts the developing sleeve. In particular, as shown in FIG. 2, when the longitudinal length of the free end of the stirring sheet is longer than the toner coat area (image forming area) of the developing sleeve, the stirring sheet is applied to the entire area of the developing sleeve where the toner is coated. It is possible to make contact. For this reason, the toner on the developing sleeve is effectively peeled off over the entire length. Thereby, the toner on the developing sleeve is not repeatedly restricted by the developing blade in the entire longitudinal region, and occurrence of toner fusion on the surface of the developing sleeve can be reduced.

  In the present embodiment, not only the surface of the stirring sheet is in contact with the surface of the developing sleeve, but also the tip of the stirring sheet is in contact with the surface of the developing sleeve (see FIG. 2). Further, in the contact area, the contacted portions are defined as the contact portions (31a, 34d), and the moving directions of the contact portions (31a, 34d) are the same direction. The contact portions (31a, 34d) are generated at the time of contact, and are present in both the stirring sheet and the developing sleeve.

(2) Speed of Stirring Sheet and Developing Sleeve The developing sleeve 31 employed in this embodiment has an outer diameter of φ11 mm and rotates in the direction of arrow R1 (first rotation direction). The distance between the rotation center of the developing sleeve and the rotation center of the stirring sheet 34a is 31 mm, and the leading end of the stirring sheet 34a rotates in the direction R2 (second rotation direction) with a radius of 26 mm around the stirring shaft. . As can be understood from FIG. 1, the first rotation direction and the second rotation direction are opposite directions. In this configuration, the developing sleeve and the stirring sheet contact each other with an intrusion amount of 5 mm when the stirring sheet does not work.

  At this time, the peripheral speed of the developing sleeve 31 is faster than the speed of the stirring sheet (speed of the stirring member 34) and passes the stirring sheet at a relative speed of 175 mm / sec. In this case, the peripheral speed of the developing sleeve is about 232 mm / sec, and the speed of the stirring member is about 57 mm / sec. Here, the speed of the stirring member 34 is a moving speed of a circle drawn by the free end (tip portion) of the stirring sheet 34a (assuming that there is no obstacle). When rotated with such a setting, the tip of the stirring sheet can scrape off the toner of about 4 mm around the developing sleeve during one contact, and when the stirring sheet rotates about 10 times, the toner on the entire developing sleeve Can be scraped off.

  Thus, in this embodiment, the developer carrying member (developing sleeve 31) is rotated in the first rotation direction (R1), and the stirring member 34 is in the second rotation direction that is opposite to the first rotation direction. By rotating to (R2), when the stirring member and the developing carrier are in contact with each other, the contact portions 31a and 34d of the developer carrying member and the stirring member move along the same moving direction. Further, the moving speed of the contact portion in the developer carrier becomes faster than the moving speed of the contact portion in the stirring member.

  The effect of removing the toner while the stirring sheet is in contact with the developing sleeve is determined by the state of the nip between the developing sleeve and the stirring sheet and the toner density in the region where the toner on the surface of the developing sleeve is peeled off. Since the toner can be effectively removed by the forward contact between the stirring sheet and the developing sleeve, details will be described below.

  FIG. 4A shows contact portions (31a, 34d) between the stirring sheet and the developing sleeve. The flexible stirring sheet contacts the surface of the developing sleeve in a state as shown in FIG. Immediately after contact, the edge portion of the stirring sheet does not contact the surface of the developing sleeve as shown in FIG. In this state, the nip formed by the stirring sheet and the developing sleeve is widened and the pressure is dispersed, so that the effect of peeling off the toner on the surface of the developing sleeve has a certain degree but is small.

  Thereafter, as shown in FIG. 4B, the contact state of the stirring sheet with the developing sleeve is an edge contact state in which the edge portion of the stirring sheet contacts the surface of the developing sleeve. In this state, since the nip portion is narrow, the peak pressure increases, and the effect of peeling off the toner on the surface of the developing sleeve is greater than the state of FIG. In addition, since the stirring sheet is immediately after supplying the toner to the developing sleeve, the toner in the region below the nip in the direction of gravity (the dotted B region) is a sparse state where the toner on the surface of the developing sleeve is peeled off. is there. For this reason, the toner that has been peeled off can be moved to the region B in FIG. That is, there is a higher toner peeling effect in the above-described nip state and the sparse toner density region in the lower region in the direction of gravity. Thereafter, the edge contact state is released after a lapse of a certain time, and the stirring sheet moves away from the developing sleeve. As a result, the toner on the developing sleeve is effectively peeled off every time the developing sleeve and the agitating sheet come into contact with each other, so that the toner is not repeatedly restricted by the developing blade and the toner is fused to the surface of the developing sleeve. Can be reduced.

  As can be understood from FIG. 4B, when the stirring member 34 and the developing sleeve 31 (developer carrier) are in contact with each other, the end surface 34a2 of the free end 34a1 of the stirring sheet is in the contact region. Is bent and deformed in the direction opposite to the moving direction of the developing sleeve 31. Thereby, the contact state between the edge portion (end surface 34a2) of the stirring sheet 34a and the surface (outer peripheral surface) of the developing sleeve 41 is improved, and the adhered matter can be more effectively peeled off.

  In this embodiment, the ratio of the moving speed of the developing sleeve (about 232 mm / sec) / the moving speed of the stirring member (about 57 mm / sec) is about four times, but is not limited to this. . This ratio is preferably in the range of 2 to 8 times. Even 10 times or less is possible. If it is larger than 10 times, there is a possibility that the toner of the developing sleeve cannot be sufficiently supplied in the configuration of this embodiment. However, depending on the configuration, it may be larger than 10 times.

  In this embodiment, since the stirring sheet is broken by the weight of the toner, the contact between the stirring sheet and the developing sleeve does not occur at the beginning of the development life. However, in the latter half of the life when the toner self-weight is reduced, the contact as described above occurs. As a result, the developing sleeve and the stirring sheet can be effectively brought into contact with each other in the latter half of the lifetime (second half of the use period) in which toner fusion is likely to occur. In addition, since the surface of the developing sleeve can be prevented from being deteriorated as compared with the case where the contact is made from the beginning of the life, the configuration is more preferable. In other words, it can be considered that when the developer amount is a predetermined amount or more, the stirring sheet does not contact the developing sleeve, and when the developer amount is less than the predetermined amount, the stirring sheet contacts the developing sleeve.

  The stirring sheet employed in this example employs a polycarbonate having a thickness of 178 μm, but this is not restrictive. Plastics such as PET (polyethylene terephthalate) and ABS (copolymerized synthetic resin of acrylonitrile, butadiene, styrene) may be used. The thickness may be designed in consideration of the stripping effect.

  Similarly, the diameter of the developing sleeve, the length of the stirring sheet, the speed of each member, and the like are not limited to the present embodiment.

  The drive source for driving the developer carrier and the stirring member may be a common drive source (for example, a motor) provided in the image forming apparatus, or may be a separate drive source (for example, a plurality of motors).

  When the developer carrying member and the stirring member are driven by separate drive sources, the respective speeds can be controlled independently by the control means 101 (shown in FIG. 5).

  On the other hand, when the developer carrier and the stirring member are driven by a common drive source, the developer carrier is made different by changing the gear diameters for transmitting the driving force to the developer carrier and the stirring member. And a predetermined peripheral speed difference in the contact area of the stirring member (difference in moving speed at the contact portion).

  FIG. 5 is a schematic diagram showing a driving configuration for driving the developing sleeve 31 and the stirring member 34 of the present embodiment.

  As shown in FIG. 5, in this embodiment, the developing device is configured to form a driving force receiving unit that engages with the driving force output unit 1011 of the main body of the image forming apparatus and receives the driving force from the driving force output unit 1011. A joint member 1012 is provided.

  In addition, the developing device includes a driving force transmission unit (gear unit 1013) that transmits the driving force received from the main body of the image forming apparatus to the developer carrier 31 and the stirring member 34 by the driving force receiving unit (engaging member 1012). A gear portion 1014 and a gear portion 1015).

  In this embodiment, the gear portion 1013 and the engaging member 1012 are integrally formed and can rotate coaxially. Moreover, the gear part 1014 and the gear part 1015 are also integrally formed, and can rotate coaxially.

  The gear portion 1013 is engaged with a gear portion 3101 disposed coaxially with the rotation shaft of the developing sleeve 31, and the driving force from the main body can be transmitted to the developing sleeve by the gear portion 1013.

  Further, the gear portion 3401 disposed coaxially with the shaft 34C of the stirring member 34 is engaged with the gear portion 1014. On the other hand, the gear portion 1013 is engaged with the gear portion 1015. Accordingly, the driving force from the main body can be transmitted to the stirring member via the gear portion 1013, the gear portion 1014, and the gear portion 1015.

  As described above, when the developing device is mounted on the main body of the image forming apparatus, the driving force receiving portion (engaging member 1012) is engaged with the driving output portion 1011 of the main body, so that the driving force transmitting portions (1013 to 1015). ), The driving force can be transmitted from the main body to the developing device side.

  In this embodiment, the driving force output unit 1011 arranged in the image forming apparatus main body is driven by a motor (not shown) controlled by the control means 101 of the apparatus main body.

<Comparative example>
Compared to the present embodiment, the toner on the developing sleeve will be described below when the stirring sheet contacts in the direction opposite to the traveling direction of the developing sleeve. The same developing sleeve, stirring sheet, distance between the rotation centers, and moving speed as in this embodiment are used. In this case, the developing sleeve contacts the leading edge of the stirring sheet at a cycle of once every 1.43 seconds as in the forward contact. In the meantime, the stirring sheet collides with the developing sleeve at a relative speed of 288.62 mm / sec, and comes into contact with the toner of the developing sleeve peripheral surface of 6.1 mm. Each time the stirring sheet rotates 5.84 times, the toner on the entire developing sleeve can be scraped off.

  FIG. 7 shows a state immediately after the stirring sheet comes into contact with the developing sleeve in the opposite direction. As shown in FIG. 7, in the state where the tip of the stirring sheet is not in contact with the surface of the developing sleeve, the effect of peeling off the surface of the developing sleeve is small because the nip is widened and the pressure is dispersed. Further, the toner in the region below the gravitational direction is denser than the nip portion where the toner on the surface of the developing sleeve is peeled off. Since it becomes difficult for the toner that has been peeled off from the developing sleeve to leave the vicinity of the surface of the developing sleeve, the toner that has been once peeled off is also attracted to the developing sleeve by a magnetic force. As a result, when the stirring sheet rotates and contacts the developing sleeve in the opposite direction, the toner on the developing sleeve cannot be effectively peeled off and is repeatedly restricted by the developing blade. In other words, the toner is fused.

(Example 2)
The second embodiment employs a cleanerless system, and differs from the first embodiment in that there is no cleaning device 8 and contact development in which development is performed in a state where the image carrier and the development carrier are in contact with each other. .

<Cleanerless system>
A cleanerless system is a structure in which a developer image (image) formed on an image carrier such as a photosensitive drum is transferred to a recording medium and the developer remaining on the image carrier is collected by the developer carrier. That means. The cleanerless system does not include a configuration in which the cleaning device is disposed and the image carrier surface is cleaned by the time the image carrier surface reaches the position facing the developer carrier after the transfer.

  More specifically, the cleanerless system in the present embodiment will be described with reference to FIG. The transfer residual toner remaining on the photosensitive drum 1 after the transfer process is charged to a negative polarity like the photosensitive drum 1 by the discharge generated between the charging roller 2 and the photosensitive drum 1. At this time, the surface of the photosensitive drum 1 is charged to −700V. The transfer residual toner charged to the negative polarity passes through the charging portion without adhering to the charging roller 2 due to the potential difference (surface potential of the photosensitive drum 1 = −700 V, charging roller potential = −1300 V).

  The untransferred toner that has passed through the charging unit reaches a laser irradiation position on the surface of the photosensitive drum 1 where the laser beam is irradiated from the laser beam scanner 4. Since the transfer residual toner is not so large as to block the laser beam of the laser beam scanner 4, it does not affect the process of forming an electrostatic image (latent image) on the photosensitive drum 1. Of the toner that has passed through the laser irradiation position, the toner in the non-exposed portion (the surface of the photosensitive drum 1 that has not received the laser irradiation) is collected in the developing sleeve 31 by electrostatic force in the developing portion. Such toner is further collected by the developing device 3 via the developing sleeve 31.

  On the other hand, of the toner that has passed through the laser irradiation position, the toner in the exposed portion (the surface of the photosensitive drum 1 that has received the laser irradiation) remains on the photosensitive drum 1 as it is without being recovered electrostatically. However, a part of the toner may be collected by a physical force due to a difference in peripheral speed between the developing sleeve 31 and the photosensitive drum 1. Such toner is also collected by the developing device 4 via the developing sleeve 31.

  The toner remaining on the photosensitive drum 1 without being transferred is generally collected by the developing device 3 except for the toner in the exposed portion. The toner collected by the developing device 3 is mixed with the toner stored in the developing device 3 and used again.

  That is, the developing device 3 simultaneously develops the latent image and collects the toner remaining on the photosensitive drum 1.

  In this embodiment, contact development is used in which development is performed while the surface of the developing sleeve and the surface of the photosensitive drum are in contact with each other. The surface of the developing sleeve has a rubber layer and contacts the photosensitive drum with an intrusion amount. The toner is efficiently collected by rotating the developing sleeve in contact with the photosensitive drum at a peripheral speed of 140%.

  In this embodiment, the charging roller 2 is driven with a peripheral speed difference of 110% with respect to the photosensitive drum 1. The charging roller driving gear is configured to receive a driving force by engaging with a gear formed on a coupling member provided on the photosensitive drum 1.

  When the charging roller 2 is driven with a peripheral speed difference with respect to the photosensitive drum 1, the adhering matter adhering to the charging roller 2 can be negated by rubbing at the contact portion with the photosensitive drum 1. As a result, due to the potential difference between the charging roller 2 and the photosensitive drum 1, the adhering matter can be returned to the photosensitive drum 1, and contamination on the surface of the charging roller 2 can be reduced.

<Image damage caused by foreign matter>
In the cleaner-less configuration, paper dust may be supplied from the paper to the photosensitive drum during transfer. When the toner is collected by the developing device, paper dust is supplied from the photosensitive drum onto the developing sleeve, and foreign matter is also included in the toner coat on the developing sleeve. As the number of printed sheets increases, the amount of paper dust in the developing sleeve increases, foreign matter gets caught in the nip between the developing sleeve and the developing blade, disturbs the toner coat on the developing sleeve, and causes vertical streak-like image damage. May cause.

  For the above reasons, in the cleaner-less configuration, the adverse effect of the image caused by the increase in the amount of foreign matter on the developing sleeve hinders the extension of the cartridge life (prolongation of the use period).

<Abutting configuration of stirring sheet and developing sleeve>
Similar to the first embodiment, in this embodiment, by bringing the stirring sheet and the developing sleeve into contact with each other in the forward direction in the stirring cycle, the foreign matter can be peeled off from the developing sleeve and the amount of adhesion on the developing sleeve can be reduced. As a result, image defects caused by foreign matter are reduced, and the life of the cartridge is extended. Further, the contact development can reduce the influence of vibration when the stirring sheet comes into contact with the developer carrying member.

  The conditions of the developing sleeve diameter, the stirring sheet length and thickness, the material, the distance between the developing sleeve and the stirring sheet, the speed of each member, and the mechanism for stripping off foreign matter on the developing sleeve are the same as in the first embodiment. Since there is, description is abbreviate | omitted.

<Others>
In the above description of the embodiments, what is detachable from the apparatus main body is not explicitly described, but there are various forms.

  For example, in the first embodiment, the image carrier, the charging member, the cleaning device, and the developing device may be used as a process cartridge integrally formed into a cartridge, and the process cartridge may be detachable from the apparatus main body. Further, instead of the process cartridge, the developing device may be detachably attached to the main body of the image forming apparatus. Further, when the developing device is detachably attached to the apparatus main body, the image carrier, the charging member, and the cleaning device may be made into a constant cartridge to form an image carrier cartridge (drum cartridge). In this case, the developing device and the image carrier cartridge are separately detachable from the apparatus main body.

  The developing device may be detachable independently, and the image carrier may be fixed to the apparatus main body.

  Of course, this can be used not only in the first embodiment but also in the cleaner-less configuration of the second embodiment.

  In the embodiments described so far, the description has been given of the configuration in which the stirring sheet as the sheet member contacts the developing sleeve as the developer carrying member, but the present invention is not limited to this. For example, instead of a sheet member, a brush-like member or a comb-like member may be used. The toner at the tip can be peeled off by giving a certain degree of hardness to the portion in contact with the developer carrying member. Moreover, even if it is a sheet | seat member, there may be a slit and a cut | interruption in the front-end | tip.

  The developer carrying member is not limited to a hollow developing sleeve, and may be a developing roller.

1 Photosensitive drum 31 Developing sleeve 34 Stirring member 34a Stirring shaft 34b Stirring sheet

Claims (19)

A developer carrying body for carrying the developer and forming an image by rotating the developer to adhere to the image carrying body; and
An agitating member for agitating the developer, comprising: a rotating member that rotates; and a flexible sheet member that is attached to the rotating member, wherein a free end of the sheet member is within an image forming region of the developer carrier. A stirring member configured to be in contact with the surface of
The developer carrier rotates in a first rotation direction;
The stirring member rotates in a second rotation direction that is opposite to the first rotation direction;
The developing device according to claim 1, wherein a moving speed of the developer carrying member is higher than a moving speed of the stirring member in a contact region where the stirring member and the developing carrier are in contact with each other. When the amount of developer is a predetermined amount or more, the stirring member does not contact the developer carrier,
The developing device according to claim 1, wherein when the amount of the developer is less than the predetermined amount, the stirring member contacts the developer carrier.   3. The developing device according to claim 1, wherein the stirring member comes into contact with the developer carrying member in the second half of the life of the developing device.   When the stirring member and the developer carrier are in contact with each other, the sheet member is bent so that an end surface at the free end of the sheet member is directed in a direction opposite to the moving direction of the developer carrier in the contact region. The developing device according to claim 1, wherein the developing device is deformed.   5. The developer carrying member according to claim 1, wherein the developer carrying member collects the developer remaining on the image carrying member after the image formed on the image carrying member is transferred to a recording medium. 2. The developing device according to item 1.   6. The apparatus according to claim 1, wherein in a posture during use, a bottom of the developer storage chamber in which the developer is stored is lower than a lowermost part of the developer carrying member. Development device. The stirring member is disposed in the developer accommodating chamber,
The developing device according to claim 6, wherein the sheet member is configured to be able to contact a bottom portion of the developer storage chamber. A developing chamber in which the developer carrying member is disposed;
The developing device according to claim 7, wherein the developing chamber has an opening for receiving the developer from the developer containing chamber.   The developing device according to claim 1, wherein a magnetic material is included in the developer carrying member.   The developing device according to claim 1, wherein the developer is a magnetic developer.   The developing device according to claim 1, wherein the developer is a one-component developer.   The developing device according to claim 1, wherein when the stirring member does not rotate, the stirring member and the developer carrying member do not come into contact with each other. The developing device is configured to be detachable from the main body of the image forming apparatus,
A driving force receiving portion for receiving a driving force from the main body of the image forming apparatus;
The driving force transmitting unit that transmits the driving force received from the main body of the image forming apparatus by the driving force receiving unit to the stirring member and the developer carrier. The developing device according to claim 1. A developer carrier that carries a developer and attaches the developer to the image carrier by rotating to form an image, and the image formed on the image carrier is transferred to a recording medium A developer carrier for recovering the developer remaining on the image carrier;
An agitating member for agitating the developer by rotating, the agitating member configured to come into contact with the surface in the image forming region of the developer carrying member when rotating,
The developer carrier rotates in a first rotation direction;
The stirring member rotates in a second rotation direction that is opposite to the first rotation direction;
The developing device according to claim 1, wherein a moving speed of the developer carrying member is higher than a moving speed of the stirring member in a contact region where the stirring member and the developing carrier are in contact with each other.   A process cartridge comprising: the image carrier; and the developing device according to claim 1.   The process cartridge according to claim 15, wherein the image formation is performed in a state where the image carrier and the developer carrier are in contact with each other.   An image forming apparatus comprising the developing device according to claim 1, and forming an image on a recording medium.   An image forming apparatus comprising the process cartridge according to claim 15 or 16 and forming an image on a recording medium. A developer carrying member for carrying the developer and forming an image by rotating and attaching the developer to the image carrier, and
An agitating member for agitating the developer, comprising: a rotating member that rotates; and a flexible sheet member that is attached to the rotating member, wherein a free end of the sheet member is within an image forming region of the developer carrier. A stirring member configured to be in contact with the surface of
The developer carrier is rotated in a first rotation direction, the stirring member is rotated in a second rotation direction that is opposite to the first rotation direction, and the stirring member and the development carrier are in contact with each other. An image forming apparatus comprising: a control unit configured to control a moving speed of the developer carrying member to be higher than a moving speed of the stirring member in the contact area.

Images