JP6727979B2 - Developing device, process cartridge and image forming device - Google Patents

Description

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

Here, the process cartridge is 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 into 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 one having at least a developer carrying member. In many cases, the developer carrying member, the developing frame member that supports the developer carrying member, and the parts related thereto are integrated and can be attached to and detached from the apparatus body of the image forming apparatus.

In an electrophotographic image forming apparatus using an electrophotographic system 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 a toner carrier by a toner carrier 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 the electrostatic latent image forming portion on the image bearing member that carries the image, and the electrostatic latent image on the photoreceptor serving as the image bearing member is moved. Visualize the image. Thereafter, this visible image is transferred to a transfer material such as paper by a transfer unit and fixed by a fixing device. The toner that has not been transferred to the transfer material and remains on the image carrier is peeled off from the image carrier by the cleaning device that is in contact with the image carrier and sent to the cleaning container. After this series of image forming processes is completed, the user can obtain a desired image.

Further, as one of the developing methods, a jumping developing method is known in which a latent image on the image carrier is developed while the developer carrier of the image forming apparatus is held in non-contact with the image carrier. Here, an example of a developing device adopting the jumping developing method will be described.

In the developing device using the jumping developing method, the toner contained in the developing container is carried by a stirring sheet or the like and held on a developing sleeve as a developer carrying member. By the rotation of the developing sleeve, 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 the blade that is in contact with the developing sleeve and is applied in a thin layer on the developing sleeve. In the developing area, the developing sleeve and the photoconductor are held with a gap of 50 to 500 μm. Then, by applying a developing bias in which a direct current and an alternating current are superimposed on the developing sleeve, the toner coated in a thin layer on the developing sleeve flies to the electrostatic latent image on the photoconductor and adheres to the latent image. Is visualized as a toner image.

As a means for achieving such a long life of the developing device (longer usage period), there is a method in which a stirring sheet, which is a stirring member, is rotated in the same direction as the rotation direction of the developer carrying member and brought into contact therewith. It is known (Patent Document 1). The structure of this developing device is shown in FIG. By bringing a stirring sheet, which is a stirring member, into contact with the developer carrier, it is possible to prevent the toner from entraining to the developing sleeve and the accumulation of the developer carrier due to foreign matters such as paper dust and other fine powder. As a result, the deposition of deposits on the surface of the developing sleeve is reduced, and a technique for extending the life of the developing device is disclosed by prolonging the period until the image is affected.

JP 2001-117369 A

However, with the configuration of Patent Document 1, it is not possible to sufficiently reduce the deposits on the developer carrying member. For example, there are cases where the area where the toner comes off from the developer carrier and the area where the toner is conveyed on the developer carrier overlap. In this case, since the toner is in a dense state (area C surrounded by a dotted line in FIG. 7), it is not possible to sufficiently reduce the amount of adhered substances such as entrainment of the toner and the long life of the developing device. Is difficult to achieve (longer usage period).

The developing device of the present invention is
A developer carrier that carries a developer and rotates to adhere the developer to the image carrier to form an image,
A stirring member for stirring a developer, comprising a rotating rotating member and a flexible sheet member attached to the rotating member, wherein a free end of the sheet member is within an image forming area of the developer carrier. A stirring member configured to be capable of contacting 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,
In a contact zone where the developer carrying member and the agitation member contacts the developing device moving speed of the developer carrying member, and wherein the faster than the moving speed of the stirring member.

Further, another developing device of the present invention is
A developer carrying member for carrying a developer and adhering the developer to an image carrying member by rotating to form an image, wherein an image formed on the image carrying member is transferred to a recording medium. And a developer carrier for collecting the developer remaining on the image carrier,
A stirring member that stirs the developer by rotating, and a stirring member that is configured to be capable of contacting the surface in the image forming region of the developer carrier 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,
In a contact zone where the developer carrying member and the agitation member contacts the developing device moving speed of the developer carrying member, and wherein the faster than the moving speed of the stirring member.

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

As described above, it is possible to lengthen the usage period of the developing device by efficiently removing the adhered matter that has adhered to the developer carrying member.

Schematic cross-sectional view of the developing device according to the present invention described in Embodiment 1. Schematic showing the positional relationship between the developing sleeve and the stirring member viewed from the X direction in FIG. A schematic cross-sectional view of an image forming apparatus according to the present invention described in Embodiment 1. Schematic diagram showing the movement of the developing sleeve and the stirring sheet described in Embodiment 1 rotating in the same direction when viewed from the contact portion. A conceptual diagram showing a driving configuration of the developing sleeve and the stirring member described in Embodiment 1. A schematic cross-sectional view of an image forming apparatus using the cleanerless system described in Embodiment 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)
An image forming apparatus according to the present invention will be described below with reference to the drawings. The examples described below are for exemplifying the present invention, and the dimensions, materials, shapes, relative positions, 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 the image forming apparatus according to the present invention. This image forming apparatus is a monochrome laser printer using an electrophotographic process.

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

The photosensitive drum 1, which is an image carrier that is rotationally driven, is uniformly charged by a charging roller 2, which is a charging member. The uniformly charged photosensitive drum 1 is exposed by a laser beam L from a scanner unit 4 which is an exposing unit, and an electrostatic latent image (or an electrostatic image) is formed on the surface of the photosensitive drum 1. Thereafter, the electrostatic latent image is visualized as a developer image by the developer supplied by the 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 accommodation unit 70 by the recording medium supply unit 71, synchronized with the timing of forming the developer image on the photosensitive drum 1, and the transfer roller 5 as the transfer unit and the photosensitive drum. The recording medium P is sent out to the portion (transfer portion) facing the recording medium 1.

In this way, 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 on which the developer image is transferred is conveyed to the fixing unit 6. Here, the unfixed toner image on the recording medium P is fixed on the recording medium P by heat and pressure. After that, the recording medium P is discharged outside the apparatus main body of the image forming apparatus by a discharge roller or the like. On the other hand, the transfer residual developer remaining on the photosensitive drum 1 after the transfer of the developer image is removed by the cleaning device 8, and the next image forming process is performed.

<Description of developing device>
In this embodiment, the 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 structure is shown in FIGS. 1 and 2. The developing device of this embodiment is configured to be attachable to and detachable from the main body of the image forming apparatus.

FIG. 1 shows the position (posture in use) of the developing device when the developing device is mounted on the main body of the image forming apparatus. FIG. 2 shows the positional relationship between the developing sleeve and the stirring member as seen from the X direction in FIG. Specifically, FIG. 2 shows a contact state when a free end 34a1 of a stirring member described later contacts the outer peripheral surface of the developing sleeve 31. The vertical direction shown in FIG. 2 is the longitudinal direction of the developing sleeve.

Further, as shown in FIG. 1, in the mounting position, the lowermost portion of the developer carrying member is located above the bottom of the developer containing chamber (toner container 300) that contains the developer. Conversely, the bottom of the developer storage chamber is located lower than the lowermost portion of the developer carrier. It has a so-called pumping configuration.

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

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

The developing sleeve 31 is formed by coating a coating material in which carbon is dispersed on a base tube 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 is rotated in the R1 direction of FIG. 1 from the photoconductor 1 via the gear. The developing sleeve 31 is connected to a power source capable of superimposing an AC bias on a DC bias, and the latent image on the photosensitive drum 1 is visualized as a toner image by applying a bias from the power source. Further, the developing sleeve 31 is opposed to and supported by the photosensitive drum 1 with a predetermined developing interval. The developing blade 33, which is a toner layer thickness regulating member that regulates the layer thickness (coating amount) of the toner on the developing sleeve 31, imparts proper 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 arranged. The magnet roller 32 has magnetic poles in four directions as shown in the drawing. Of the four magnetic poles, the S2 pole is necessary to keep the toner, which causes fog, on the developing sleeve 31 when the toner flies onto the photosensitive drum 1 and is developed. The S1 pole is arranged on the opposite side of the S2 pole, and attracts the toner in the developing container 301 to the developing sleeve 31. The N1 and N2 poles both contribute to the conveyance of the toner coated on the developing sleeve 31 and the provision of tribo. In this embodiment, a magnet roller having a four-pole structure is used, but the number of poles is not limited to four as long as there are poles that fulfill the above functions.

As described above, in this embodiment, the developer carrying member (developing sleeve 31) carries the developer and is rotated to adhere the developer to the image carrying member (developer image) to form an image. The composition.

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

The stirring member has a stirring sheet 34a, which is a flexible sheet member, fixed to a 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 the free end 34a1. The center of the stirring shaft portion 34b becomes the rotation center 34c, which is the axis of the stirring shaft.

The agitating sheet 34a comes into contact with the bottom of the toner container with a certain amount of penetration to loosen the toner contained in the toner container 300. Further, when the stirring sheet 34a rubs against the bottom of the toner container and rotates, the toner is transported from the toner container 300 to the developing container 301.

The agitating sheet 34a carrying the toner rotates in the R2 direction in FIG. 1 and contacts the developing sleeve 31.

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.

In this way, the stirring member rotates to stir the developer. Further, the stirring member is configured so as to be able 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 carrying body is an area on the developer carrying body corresponding to the area of the electrostatic latent image formed on the image carrying body.

When the stirring member is not rotating except for a specific stop position, 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.

Further, the stirring member 34 is arranged in the developer accommodating chamber, and the stirring sheet 34a has a length capable of contacting the bottom of the developer accommodating chamber. Accordingly, the stirring member can easily stir the developer in the vicinity of the bottom of the stirring developer storage chamber.

<Toner fusion>
The toner charge amount and the layer thickness on the developing sleeve 31 depend on the state of the developing sleeve surface and the like. Therefore, in order to maintain uniform image quality throughout the life of the cartridge, it is necessary to reduce changes in the surface condition of the developing sleeve throughout the life of the cartridge. Toner fusion may be mentioned as a change in the surface state of the developing sleeve, which is a factor that determines the life of the cartridge. The process for forming the toner fusion on 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 cartridge and the temperature of the toner increase. Particularly in severe use under a high temperature and high humidity environment, when the toner is heated to a temperature close to the glass transition point, the toner becomes soft and easily deteriorates. In this state, when the toner consumption on the developing sleeve is small and printing with a low printing rate is repeated, toner circulation on the developing sleeve does not actively occur, 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, tribo decreases due to a change in the sleeve surface layer, and fluctuations (change) in the toner conveyance amount on the sleeve due to a change in the surface roughness of the sleeve occur, making it difficult to form an appropriate image. It will be necessary to replace the cartridge. In such a case, it is not possible to sufficiently extend the usage period of the cartridge.

<Agitating sheet and developing sleeve contact structure>
Next, the contact structure between the stirring sheet and the developing sleeve will be described.

In this embodiment, in order to effectively strip off 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 higher than the peripheral speed (moving speed) of the stirring sheet.

Specifically, the developer carrying member (developing sleeve 31) rotates in the first rotation direction (R1), and the stirring member 34 rotates in the second rotation direction (R2) that is the opposite direction to the first rotation direction. To do. Further, in the contact area where the stirring member and the developer carrying member come into 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 contact portion (34d) of the stirring member. Is also set faster.

(1) Rotational Direction of Stirring Sheet and Developing Sleeve By employing the above-described configuration, the toner on the developing sleeve is scraped off every time the stirring sheet contacts the developing sleeve. In particular, as shown in FIG. 2, when the length in the longitudinal direction of the free end of the stirring sheet is longer than the toner coating area (image forming area) of the developing sleeve, the stirring sheet is spread over the toner coating area of the developing sleeve. It is possible to make contact. Therefore, the toner on the developing sleeve is effectively stripped off over the entire length. As a result, the toner on the developing sleeve is not repeatedly regulated by the developing blade in the entire longitudinal direction, and it is possible to reduce the occurrence of toner fusion on the surface of the developing sleeve.

In this embodiment, not only the surface of the stirring sheet contacts the surface of the developing sleeve, but also the tip of the stirring sheet contacts the surface of the developing sleeve (see FIG. 2). Further, in the contact area, the contacting portions are contact portions (31a, 34d), and the moving directions of the contact portions (31a, 34d) are the same. The contact portions (31a, 34d) are generated when they come into contact with each other, and are present on both the stirring sheet and the developing sleeve.

(2) Speed of stirring sheet and developing sleeve The outer diameter of the developing sleeve 31 employed in this embodiment is φ11 mm, and it rotates in the direction of arrow R1 (first rotating 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 tip of the stirring sheet 34a rotates in the radius R of 26 mm around the stirring shaft in the R2 direction (second rotation direction) in the figure. .. As can be understood from FIG. 1, the first rotation direction and the second rotation direction are directions opposite to each other. With this configuration, the developing sleeve and the stirring sheet come into contact with each other with a penetration amount of 5 mm when the stirring sheet does not move.

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 over 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 the moving speed of a circle drawn by the free end (tip portion) of the stirring sheet 34a (assuming that there is no obstacle). If the stirring sheet is rotated at such a setting, the tip of the stirring sheet can scrape off the toner on the developing sleeve circumferential surface of about 4 mm during one contact, and when the stirring sheet rotates about 10 times, the toner of the entire developing sleeve is rotated. 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 rotated in the second rotation direction which is the opposite direction to the first rotation direction. By rotating to (R2), when the agitating member and the developing member come into contact with each other, the contact portions 31a and 34d of the developer carrying member and the agitating member move along the same moving direction. Further, the moving speed of the contact portion of the developer carrying member is faster than the moving speed of the contact portion of the stirring member.

The effect of stripping toner while the agitating sheet is in contact with the developing sleeve is determined by the state of the nip between the developing sleeve and the agitating sheet and the toner density in the area where the toner comes off on the surface of the developing sleeve. The toner can be effectively peeled off by contacting the stirring sheet and the developing sleeve in the forward direction, and the details will be described below.

FIG. 4A shows the contact portions (31a, 34d) between the stirring sheet and the developing sleeve. The flexible stirring sheet comes into contact with the surface of the developing sleeve in the state as shown in FIG. Immediately after the contact, as shown in FIG. 4A, the edge portion of the stirring sheet does not contact the surface of the developing sleeve. In this state, the nip portion formed by the agitating sheet and the developing sleeve becomes wider and the pressure is dispersed, so that the effect of peeling off the toner on the surface of the developing sleeve is small to some extent.

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 becomes large, and the effect of stripping the toner on the surface of the developing sleeve is larger than that in the state shown in FIG. 4A. Further, since the stirring sheet has just supplied the toner to the developing sleeve, the toner on the developing sleeve surface is a region in which the toner is peeled off. is there. Therefore, the peeled toner can move to the area B in FIG. 4B. In other words, the above-mentioned nip state and the region of sparse toner density in the lower region in the direction of gravity have a high toner stripping effect. After a lapse of a certain period of time, the edge contact state is released and the stirring sheet separates from the developing sleeve. As a result, the toner on the developing sleeve is effectively peeled off every time the developing sleeve and the stirring sheet come into contact with each other, so that the toner is not repeatedly regulated 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 carrying member) are in contact with each other, the stirring sheet 34a (sheet member) has a contact area where the end surface 34a2 at the free end 34a1 of the stirring sheet is in contact. The developing sleeve 31 is bent and deformed in the direction opposite to the moving direction of the developing sleeve 31. As a result, 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 adhering matter can be stripped off more effectively.

In the present 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 4 times, but it is not limited to this. .. This ratio is preferably in the range of 2 to 8 times. It can be 10 times or less. If it is more than 10 times, there is a possibility that toner cannot be sufficiently supplied to the developing sleeve in the configuration of this embodiment. However, depending on the configuration, it may be larger than 10 times.

Further, in this embodiment, the stirring sheet is bent by the weight of the toner, so that the stirring sheet and the developing sleeve do not come into contact with each other at the beginning of the development life. However, in the latter half of the life when the weight of the toner becomes small, 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 during the latter half of the service life (the latter half of the usage period) in which toner fusion is likely to occur. Further, since it is possible to prevent the surface layer of the developing sleeve from being deteriorated as compared with the case where the developing sleeve is contacted from the beginning of its life, a more preferable structure is obtained. From a different point of view, it can be considered that the agitating sheet does not come into contact with the developing sleeve when the developer amount is equal to or larger than a predetermined amount, and the agitating sheet comes into contact with the developing sleeve when the developer amount is smaller than the predetermined amount.

The stirring sheet used in this embodiment is made of polycarbonate having a thickness of 178 μm, but the invention is not limited thereto. Plastics such as PET (polyethylene terephthalate) and ABS (copolymer synthetic resin of acrylonitrile, butadiene, styrene) may be used. The thickness may also be designed in consideration of the stripping effect and the like.

Similarly, the diameter of the developing sleeve, the length of the stirring sheet, the speed of each member, etc. are not limited to those in this embodiment.

The drive source that drives the developer carrying member 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 different driving sources, the respective speeds can be independently controlled 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 varying 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 between the contact portions) can be obtained.

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

As shown in FIG. 5, in this embodiment, the developing device constitutes a driving force receiving portion that engages with the driving force output portion 1011 of the main body of the image forming apparatus and receives the driving force from the driving force output portion 1011. The composite member 1012 is provided.

The developing device also includes a driving force transmitting portion (gear portion 1013, which transmits the driving force received from the main body of the image forming apparatus by the driving force receiving portion (engaging member 1012) to the developer carrying member 31 and the stirring member 34). The gear unit 1014 and the gear unit 1015) are provided.

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

The gear portion 1013 is engaged with the gear portion 3101 arranged coaxially with the rotation axis of the developing sleeve 31, and the gear portion 1013 can transmit the driving force from the main body to the developing sleeve.

Further, the gear portion 3401 arranged 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. Therefore, 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 portion (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 unit 101 of the apparatus main body.

<Comparative example>
The peeling of the toner on the developing sleeve when the stirring sheet contacts the developing sleeve in the direction opposite to the traveling direction will be described below as compared with the present embodiment. The same developing sleeve, stirring sheet, distance between each rotation center, and moving speed as in this embodiment are used. In this case, the developing sleeve comes into contact with the tip of the stirring sheet at a cycle of once every 1.43 seconds, as in the case of contact in the forward direction. Meanwhile, the agitating sheet collides with the developing sleeve at a relative speed of 288.62 mm/sec and comes into contact with the toner on the developing sleeve peripheral surface of 6.1 mm. Every 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, when the tip portion of the stirring sheet is not in contact with the surface of the developing sleeve, the nip portion is widened and the pressure is dispersed, so that the effect of peeling off the surface of the developing sleeve is small. Further, the toner in the area below the nip portion, which is the area where the toner peels off on the surface of the developing sleeve, is in a dense state. Since it becomes difficult for the toner that has peeled off from the developing sleeve to separate from the vicinity of the surface of the developing sleeve, the toner that has once peeled off is also attracted to the developing sleeve by the magnetic force. As a result, when the stirring sheet rotates in the direction opposite to the developing sleeve and comes into contact with the developing sleeve, the toner on the developing sleeve cannot be effectively stripped off, and the developing blade surface is repeatedly regulated by the developing blade. The toner is fused to the.

(Example 2)
The second embodiment employs a cleanerless system, and is different from the first embodiment in that contact development is performed in a state where the image carrier and the developing carrier are in contact with each other, and that the cleaning device 8 is not provided. ..

<Cleanerless system>
The cleanerless system has a structure in which the developer image (image) formed on an image bearing member such as a photosensitive drum is transferred to a recording medium and then the developer remaining on the image bearing member is collected by the developer bearing member. Say that. The cleanerless system does not include a configuration in which the cleaning device is arranged and the surface of the image bearing member is cleaned by the time the surface of the image bearing member reaches the position facing the developer bearing member after the transfer.

More specifically, the cleanerless system in this embodiment will be described with reference to FIG. The transfer residual toner remaining on the photosensitive drum 1 after the transfer process is negatively charged 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 negatively charged passes through the charging roller 2 without being attached to the charging roller 2 due to the potential difference (surface potential of the photosensitive drum 1=−700 V, charging roller potential=−1300 V) at the charging portion.

The transfer residual toner that has passed through the charging unit reaches the 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 laser irradiation) is collected in the developing sleeve 31 by the electrostatic force in the developing portion. Then, 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 of the exposed portion (the surface of the photosensitive drum 1 that has been irradiated with the laser) remains on the photosensitive drum 1 without being electrostatically collected. However, some toner may be collected by a physical force due to the peripheral speed difference 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. Then, the toner collected in the developing device 3 is mixed with the toner contained 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.

Further, in this embodiment, contact development is employed 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 comes into contact with the photosensitive drum with a certain amount of penetration. 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.

By driving the charging roller 2 with a peripheral speed difference with respect to the photosensitive drum 1, it is possible to rub the attached matter that has adhered to the charging roller 2 at the contact portion with the photosensitive drum 1 by rubbing. As a result, due to the potential difference between the charging roller 2 and the photosensitive drum 1, the adhering substances can be returned to the photosensitive drum 1, and the dirt on the surface of the charging roller 2 can be reduced.

<Degradation of image due to foreign matter>
In the cleanerless configuration, paper dust may be supplied from the paper to the photosensitive drum during transfer. When the toner is collected in the developing device, paper powder is supplied from the photosensitive drum onto the developing sleeve, and the toner coat on the developing sleeve also contains foreign matter. As the number of printed sheets increases, the amount of paper dust in the developing sleeve increases, foreign matter gets caught in the nip part between the developing sleeve and the developing blade, disturbs the toner coat on the developing sleeve, and causes vertical stripe-shaped image damage. May cause it.

For the above reasons, in the cleanerless configuration, the image adverse effect caused by the increase in the amount of foreign matter on the developing sleeve is an obstacle to extending the life of the cartridge (extending the use period).

<Agitating sheet and developing sleeve contact structure>
Similar to the first embodiment, in this embodiment, the agitating sheet and the developing sleeve are brought into contact with each other in the forward direction in the agitating cycle, so that 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, the adverse effect on the image due to the foreign matter is 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 developing sleeve diameter, the length and thickness of the stirring sheet, the material, the distance between the developing sleeve and the stirring sheet, the speed of each member, and the like in this embodiment, and the mechanism for stripping the foreign matter on the developing sleeve are the same as in the first embodiment. Therefore, the description is omitted.

<Other>
Although the above description of the embodiments does not explicitly describe what can be attached to and detached from the apparatus main body, 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 that is integrally formed as a cartridge, and the process cartridge may be detachable from the main body of the device. Further, instead of the process cartridge, the developing device may be independently attachable to and detachable from the main body of the image forming apparatus. Further, when the developing device can be independently attached to and detached from the main body of the apparatus, 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 attachable to and detachable from the apparatus main body.

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

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

Further, in the above-described embodiments, the stirring sheet as the sheet member is described as being in contact with the developing sleeve as the developer carrying member, but the present invention is not limited to this. For example, a brush-shaped member or a comb-shaped member may be used instead of the sheet member. By giving a certain amount of hardness to the portion in contact with the developer carrying member, it is possible to peel off the toner at the tip. Further, even a sheet member may have slits or cuts at the tip.

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

1 Photosensitive Drum 31 Developing Sleeve 34 Stirring Member 34a Stirring Shaft 34b Stirring Sheet

Claims (19)

A developer carrier that carries a developer and rotates to adhere the developer to the image carrier to form an image,
An agitating member for agitating a developer, comprising a rotating rotating member and a flexible sheet member attached to the rotating member, and a free end of the sheet member is within an image forming area of the developer carrier. A stirring member configured to be capable of contacting 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,
In a contact zone where the developer carrying member and the agitation member contacts the developing device moving speed of the developer carrying member, and wherein the faster than the moving speed of the stirring member. When the amount of the developer is a predetermined amount or more, the stirring member does not come into contact with the developer carrier,
The developing device according to claim 1, wherein when the amount of the developer is smaller than the predetermined amount, the stirring member comes into contact with the developer carrier. The developing device according to claim 1, wherein the stirring member comes into contact with the developer carrying member in the latter half of the life of the developing device. When the agitating member and the developer carrying member come into contact with each other, the sheet member bends so that an end surface of the sheet member at the free end faces in a direction opposite to a moving direction of the developer carrying member in the contact region. The developing device according to claim 1, wherein the developing device is deformed. 5. 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. The developing device according to item 1. 6. The bottom of the developer accommodating chamber for accommodating the developer is lower than the lowermost part of the developer carrier in the posture during use, according to any one of claims 1 to 5. Development device. The stirring member is disposed in the developer storage chamber,
The developing device according to claim 6, wherein the sheet member is configured to be capable of contacting a bottom portion of the developer accommodating chamber. A developing chamber in which the developer carrier is placed,
The developing device according to claim 7, wherein the developing chamber has an opening for receiving the developer from the developer accommodating chamber. 9. The developing device according to claim 1, wherein the developer carrying member contains a magnetic material. 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 any one of claims 1 to 11, wherein the agitating member and the developer carrying member do not come into contact with each other when the agitating member does not rotate. The developing device is configured to be detachable from the main body of the image forming apparatus,
A driving force receiving portion that receives a driving force from the main body of the image forming apparatus;
13. The drive force transmission unit configured to transmit the drive force received from the main body of the image forming apparatus by the drive force receiving unit to the stirring member and the developer carrying member. 2. The developing device according to item 1. A developer carrying member for carrying a developer and adhering the developer to the image carrying member by rotating to form an image, wherein the image formed on the image carrying member is transferred to a recording medium. And a developer carrier for collecting the developer remaining on the image carrier,
A stirring member that stirs the developer by rotating, and a stirring member that is configured to be capable of contacting the surface in the image forming region of the developer carrier 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,
In a contact zone where the developer carrying member and the agitation member contacts the developing device moving speed of the developer carrying member, and wherein the faster than the moving speed of the stirring member. A process cartridge comprising: the image carrier; and the developing device according to claim 1. 16. 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 carrier that carries a developer and rotates to adhere the developer to the image carrier to form an image,
An agitating member for agitating a developer, comprising a rotating rotating member and a flexible sheet member attached to the rotating member, and a free end of the sheet member is within an image forming area of the developer carrier. A stirring member configured to be capable of contacting the surface of
Rotating the developer carrying member in a first rotational direction, the stirring member is rotated in a second rotational direction which is the first direction opposite to the direction of rotation, said stirring member and the developer carrying member contact And a control unit that controls the moving speed of the developer carrier to be higher than the moving speed of the stirring member in the contact area.

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