JP2006227325A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of suppressing a decrease in image quality due to toner deterioration. <P>SOLUTION: The image forming apparatus 100 which is equipped with a rotatable image carrier 1 carrying an image formed with a developer, a developing unit equipped with a container 42 containing a developer and a developer carrier 41 which rotates to carry and supply the developer in the container 42 to the image carrier, and driving means 13 and 16 of variably controlling the ratio of the peripheral speed of the developer carrier 41 to the peripheral speed of the image carrier 1, and is such that a cartridge B equipped with at least the developing unit 4 is attachable to and detachable from a primary apparatus body A is so configured that the peripheral speed ratio of the developer carrier 41 and the image carrier 1 is varied according to durability information on the cartridge B. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus using an electrophotographic system or an electrostatic recording system, such as a copying machine, a printer, or a facsimile machine.

  Conventionally, in an image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive member (photosensitive member) and at least one of charging means, developing means, and cleaning means as process means acting on the photosensitive member are integrated. There is a process cartridge system in which the cartridge is formed into a cartridge and the cartridge can be attached to and detached from the image forming apparatus main body. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved. For this reason, this process cartridge system is widely used in image forming apparatuses.

  In a process cartridge type image forming apparatus, for example, the process cartridge is replaced when the developer contained in the developing device as the developing means provided in the process cartridge is exhausted. As a result, other members such as the photosensitive member can be replaced at the same time, and the image forming apparatus can maintain good image quality.

  In some cases, the developing device is a cartridge (developing cartridge) that can be detachably attached to the main body of the image forming apparatus.

  By the way, the developer deteriorates with use. That is, the developing device includes a developer carrying member (for example, a developing roller) that conveys the developer to the photosensitive member, a developer regulating member (for example, a developing blade) that regulates the developer on the developer carrying member, and the developer. A developer conveying member (for example, a stirring blade or a stirring rod) that stirs and conveys the developer until the developer is exhausted. By rubbing for a long time. As a result, the toner in the developer becomes irregular in shape, causes a difference in particle size distribution, and is added to the developer for the purpose of improving fluidity. Titanium oxide particles, etc.) are embedded in the toner surface. As a result, deterioration such as a decrease in fluidity and chargeability of the developer occurs.

  For example, it is effective to increase the ratio of the surface movement speed of the developer carrying member to the surface movement speed of the photosensitive member for toner that is difficult to have a desired charge due to deterioration. As a result, the amount of toner adhering to the electrostatic image on the photoreceptor can be set to a desired amount, and the density of the image can be made appropriate.

  In Patent Document 1, a storage element for storing various information of the process cartridge is provided in the process cartridge, and the rotation of the developing roller is rotated according to the remaining amount information of the developer stored in the developing device stored in the storage element. Disclose changing speed. In the invention of Patent Document 1, the ratio between the rotational speed of the photosensitive member and the rotational speed of the developing roller is thereby optimally maintained in accordance with the remaining amount information of the developer.

However, it is generally difficult to accurately read the remaining amount of the developer stored in the developing device unless the developer is almost on the verge of running out of the developer. For this reason, for example, when an output image with a low printing ratio is mainly output, the developer in the developing device deteriorates despite a large amount of developer remaining. In the cartridge detachable image forming apparatus as described above, the image quality may be deteriorated even though the cartridge has not reached the end of its life. In particular, in a color image forming apparatus, since slight image quality degradation for each color is superimposed, an image forming apparatus capable of maintaining better image quality according to the durability of the process cartridge is required. .
Japanese Patent Laid-Open No. 9-190058

  An object of the present invention is to provide an image forming apparatus capable of suppressing a decrease in image quality due to developer deterioration.

  One of the more detailed objects of the present invention is to provide an image forming apparatus capable of maintaining good image quality from the beginning of use of a cartridge including a developing device to the end of its life.

  The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention relates to a rotatable image carrier that carries an image formed by a developer; a container that contains the developer; and the developer in the container that is rotated to convey the developer to the image carrier. A developer carrier provided; and a driving unit that variably controls the ratio of the peripheral speed of the developer carrier to the peripheral speed of the image carrier, and at least the developer In the image forming apparatus in which the cartridge including the image forming apparatus is detachable from the apparatus main body, the peripheral speed ratio between the developer carrier and the image carrier is changed according to the durability information of the cartridge. The image forming apparatus. The durability information of the cartridge indicates an index value that changes substantially in proportion to the amount of use of the cartridge. According to one embodiment of the present invention, the durability information of the cartridge includes the developer carrying amount. And at least one of a cumulative rotational speed of the body, a cumulative rotational speed of the image carrier, and an image output number.

  According to the present invention, it is possible to suppress a decrease in image quality due to developer deterioration. Further, according to the present invention, it is possible to maintain good image quality at least from the beginning of use of the cartridge including the developing device to the end of its life.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Example 1
[Entire configuration of image forming apparatus]
First, the overall configuration of the color image forming apparatus will be described with reference to FIG. FIG. 1 shows the overall configuration of an image forming apparatus according to the present invention. The image forming apparatus 100 according to the present embodiment responds to an image information signal from an external device such as a personal computer, an image reading apparatus, or a digital camera that is communicably connected to the image forming apparatus main body (apparatus main body) A. Using an electrophotographic method, a full-color image of four colors of yellow (Y), magenta (M), cyan (C), and black (K) is formed on a transfer material (recording paper, OHP sheet, cloth, etc.). It is a laser beam printer that can.

  The image forming apparatus 100 includes first, second, third, and fourth images that form yellow (Y), magenta (M), cyan (C), and black (K) images as image forming units, respectively. It has a so-called tandem configuration having image forming portions PY, PM, PC, and PK.

  In the image forming apparatus 100 of this embodiment, the configuration of each image forming unit PY, PM, PC, PK is substantially the same except that the color of the developer used is different. When no distinction is required, the subscripts Y, M, C, and K given to the reference numerals to indicate that they belong to an image forming unit for any color will be omitted and will be described collectively.

  The image forming unit P includes a drum-type photosensitive member as an image carrier, that is, a photosensitive drum 1 that is rotationally driven at a constant speed. Around the photosensitive drum 1, a charging roller 2 as a charging unit and a developing device 4 as a developing unit are arranged. Each image forming portion P is provided with a laser scanner 3 as an exposure means (image writing means) for irradiating the photosensitive drum 1 with light according to image information. Further, the image forming apparatus 100 is provided with a transfer unit 5 for sequentially transferring the toner images developed on the photosensitive drum 1 in each image forming portion P onto the transfer material S in sequence. The transfer unit 5 is provided with a conveyor belt 55 for carrying the transfer material S fed from the transfer material feeding unit 7 and sequentially transporting it to each image forming unit P.

  In this embodiment, in each image forming unit P, the photosensitive drum 1 and the charging roller 2 and the developing device 4 as process means acting on the photosensitive drum 1 are integrally formed into a cartridge, and the apparatus main body A is The process cartridge B is detachable individually.

  The cartridge that can be attached to and detached from the image forming apparatus main body is not limited to the embodiment. The cartridge only needs to include a developing device including a container for storing the developer and a developer carrying member for conveying the developer in the container to the photosensitive member. The developing cartridge may be detachable, or the developing device and the photosensitive member may be integrated into a cartridge, or may be a process cartridge in which at least one of charging means and cleaning means is integrated into a cartridge.

[Elements related to the image forming process]
Next, with reference to FIG. 2 as well, the configuration of each part of the image forming apparatus 100 will be described in more detail.

(Photosensitive drum)
The photosensitive drum 1 as an image carrier is rotatably supported by a container 42 of the developing device 4 and is formed into a cartridge integrally with the developing device 4 to constitute a process cartridge B. The process cartridge B is detachably supported with respect to the apparatus main body A. Therefore, the unit of the process cartridge B can be easily replaced alone according to the life of the photosensitive drum 1, for example. In this embodiment, the photosensitive drum 1 is configured by applying an organic photoconductor layer to the outside of an aluminum cylinder.

  In this embodiment, the driving force of the first driving source (first driving motor) provided in the first driving means for driving the photosensitive drum 1 is the depth of the photosensitive drum 1 in FIG. 1 and FIG. Is transmitted to one end of the. The photosensitive drum 1 is rotationally driven in the arrow direction (counterclockwise) in FIG. 2 in accordance with an image forming operation. In this embodiment, the photosensitive drum 1 is rotationally driven at a constant surface moving speed (circumferential speed).

(Charging roller)
In this embodiment, a charging roller 2 that rotates in contact with the surface of the photosensitive drum 1 is used as a charging unit. A predetermined charging bias is applied to the charging roller 2 from a charging bias power source (not shown). In this embodiment, the charging roller 2 charges the surface of the photosensitive drum 1 substantially uniformly to a negative polarity.

(Developer)
The developing device 4 includes a container 42 that stores a non-magnetic one-component developer (toner) as a developer. The container 42 is rotatably provided with a developing roller 41 as a developer carrier. The developing roller 41 is located in an opening portion of the container 42 facing the photosensitive drum 1 and rotates in proximity to or in contact with the surface of the photosensitive drum 1. Further, the developer 4 is supplied with the toner contained in the container 42 to the developing roller 41, and is also supplied with a developer for peeling off the toner from the surface of the developing roller 41 and a supply and peeling roller 43 as a peeling means. Is provided. Further, a predetermined developing bias is applied to the developing roller 41 from a developing bias power source as a voltage applying means at least during a developing operation.

  In this embodiment, the second driving means for driving the developing roller 41 of the developing device 4 is a second driving source (provided separately from the first driving source for driving the photosensitive drum 1). A second drive motor). The driving force from the second driving source is transmitted to one end of the developing roller 41 on the back side in FIG. 1 and FIG. The developing roller 41 is driven to rotate in the direction of the arrow (clockwise) in FIG. That is, the surface of the developing roller 41 moves in the same direction as the surface movement direction of the photosensitive drum 1 at a portion (developing portion) facing the photosensitive drum 1. As described above, in this embodiment, the developing roller 41 is driven by a drive source independent of the photosensitive drum 1, so that the surface movement speed (circumferential speed) of the developing roller 41 can be arbitrarily set. .

(Conveyor belt)
The transfer unit 5 is provided with a transport belt 55 as a transfer material transport member. The conveyor belt 55 is supported by the apparatus main body A with the driving roller 51 as a fulcrum, that is, by the driving roller 51, the tension roller 52, and the suction counter roller 53. The conveying belt 55 is transmitted with a driving force of a conveying belt driving source (conveying belt driving motor) to one end on the back side in FIG. Thus, the conveyance belt 55 performs multiple transfer of the toner image on the photosensitive drum 1 visualized by the developing unit 4 onto the transfer material S, in the direction of the arrow (clockwise) in FIG. 1 according to the image forming operation. Then, it is rotated (rotated) in synchronism with the peripheral speed of the photosensitive drum 1.

  A transfer roller 54 as a transfer unit is disposed at a position facing the photosensitive drum 1 of each image forming unit P with the conveying belt 55 interposed therebetween. At the position of the transfer roller 54, the conveyance belt 55 and the photosensitive drum 1 come into contact with each other to form a transfer portion (transfer nip). The toner image formed on the photosensitive drum 1 is transferred onto the transfer belt 54 by applying a predetermined transfer bias opposite to the normal charging polarity of the toner from the transfer bias power source to the transfer roller 54. Multiple transfer on S.

  The transfer material P conveyed from the transfer material feeding unit 7 is electrostatically held on the conveyance belt 55 in the adsorption unit where the adsorption roller 56 and the adsorption counter roller 53 face each other via the conveyance belt 55. Is done. The transfer material S held on the transport belt 55 is sequentially transported to the transfer section T of each image forming section P as the transport belt 55 rotates. The transfer material supply unit 7 synchronizes with the cassette 71 that houses the transfer material S, the feeding roller 72 that feeds the transfer material S from the cassette 71 one by one, and the image forming operation in the image forming unit P. A registration roller 73 for feeding out the toner.

[Image forming operation]
Next, an image forming operation by the image forming apparatus 100 having the above-described configuration will be further described.

  First, the transfer material S in the cassette 71 is separated and fed by the rotation of the feed roller 72 of the transfer material feeding unit 7 and conveyed to the registration roller 73.

  On the other hand, the photosensitive drum 1 and the conveyor belt 55 are each rotationally driven in a direction indicated by an arrow at a predetermined peripheral speed V (hereinafter referred to as “process speed”). The photosensitive drum 1 whose surface is uniformly charged by the charging roller 2 is irradiated with laser light L modulated in accordance with image information from the laser scanner 3, and an electrostatic image is formed on the photosensitive drum 1. The developing roller 41 is driven in synchronization with the formation of the electrostatic image on the photosensitive drum 1. In other words, the developing roller 41 is driven to rotate, and in this embodiment, a developing bias having the same polarity as the charging polarity of the photosensitive drum 1 and substantially the same potential is developed so that the toner adheres to the electrostatic image on the photosensitive drum 1. Applied to the roller 41. As a result, the electrostatic image formed on the photosensitive drum 1 is developed by the toner at the facing portion (developing portion) between the developing roller 41 and the photosensitive drum 1.

  The toner image formed on the photosensitive drum 1 is held and conveyed on the conveying belt 55 at the transfer portion T downstream of the developing portion where the photosensitive drum 1 and the developing roller 41 face each other in the rotation direction of the photosensitive drum 1. It is transferred to the transfer material S that has been transferred. At this time, a transfer bias having a polarity opposite to that of the toner image is applied to the transfer portion T via the transfer roller 54.

  For example, when a four-color full-color image is formed, the above process is performed separately in the four-color image forming portions PY, PM, PC, and PK of yellow, magenta, cyan, and black, and the toner image on the transfer material S is formed. The timing is such that the tips coincide. As a result, four color toner images are transferred onto the transfer material S in a multiple manner.

  The transfer material S is transported from the registration roller 73 to the transport belt 55 at the timing when the first color toner image reaches the transfer portion T, and is sucked and held on the transport belt 55 and transported.

  The transfer material S on which the toner images of four colors are superimposed and transferred after passing through the transfer portion T of each image forming portion P is peeled off from the transport belt 55 and transported to the fixing portion 6. In the fixing unit 6, the toner on the transfer material S is melted and mixed and fixed to the transfer material S. Thereafter, the transfer material S is discharged via a discharge roller pair 81 onto a discharge tray 82 provided on the upper part of the apparatus main body A with the image surface facing downward. Thus, the image forming operation is completed.

  In this embodiment, the toner (transfer residual toner) remaining on the photosensitive drum 1 after the transfer process is collected by the developing device 4 and reused. However, a cleaning unit that removes toner from the photosensitive drum 1 may be provided separately. As a cleaning means, a blade member (cleaning blade) that contacts the photosensitive drum 1 and scrapes off the toner on the photosensitive drum 1 is generally used.

  Further, when forming a single color image such as a black and white image or a multi-color image by combining several colors, a toner image is formed only at a desired image forming portion P and transferred to the transfer material S. You can do it.

[Control of peripheral speed ratio between developing roller and photosensitive drum]
Next, the most characteristic method for controlling the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 will be described.

  As described above, in this embodiment, the process cartridge B including the photosensitive drum 1 and the developing roller 41 is detachable from the apparatus main body A. In this embodiment, the driving means for variably controlling the ratio of the peripheral speed of the developing roller 41 to the peripheral speed of the photosensitive drum 1 has a plurality of driving so that the photosensitive drum 1 and the developing roller 41 can be driven independently. Have a source.

  FIG. 4 shows a schematic control block of the image forming apparatus 100 of the present embodiment.

  The apparatus main body A controls an image forming condition and an image forming operation from various information, and exchanges information with a storage element 21 (described later) of the process cartridge B, and an electrostatic image on the photosensitive drum 1. A first scanner 13 for driving the photosensitive drum 1, a first drive source 13 for driving the photosensitive drum 1, and a first main body side for driving transmission to the first cartridge side drive transmission means 15 (described later) of the process cartridge B Drive transmission means 14, a second drive source 16 for driving the developing roller 41, and a second main body side drive transmission means 17 for driving transmission to a second cartridge side drive transmission means 18 (described later) of the process cartridge B. Etc. are provided.

  In this embodiment, the first drive source 13, the first main body side drive transmission means 14, and the first cartridge side drive transmission means 15 constitute a first drive means for driving the photosensitive drum 1. The second drive source 16, the second main body side drive transmission means 17, and the second cartridge side drive transmission means 18 constitute second drive means for driving the developing roller 41.

  On the other hand, the process cartridge B includes a storage element (memory) 21 as storage means for storing various information of the process cartridge B, the photosensitive drum 1, and first main body side drive transmission means for driving the photosensitive drum 1. The first cartridge side drive transmission means 15 to which the drive is transmitted from 14, the developing roller 41, and the second cartridge side drive to which the drive is transmitted from the second main body side drive transmission means 17 for driving the development roller 41 Transmission means 18 and the like are provided.

  As the first and second main body side drive transmission means 14 and 17, gear trains and couplings respectively connected to the first drive source 13 and the second drive source 16 are used. On the other hand, in the present embodiment, as the first cartridge side drive transmission means 15, a coupling that is integrally attached to the photosensitive drum 1 and engages with the coupling of the first main body side drive transmission means is used. As the second cartridge side drive transmission means 18, a coupling that engages with the coupling of the second main body side drive transmission means 17 and a gear train that transmits the drive from the coupling to the developing roller 41 are used. It is done.

  The memory element 21 can be appropriately selected from those known in the art as long as it can store information, but an electronic memory is preferable in terms of small size and light weight. In this embodiment, an electronic nonvolatile memory is used.

  The controller unit 11 controls each unit of the image forming apparatus 100 in accordance with an image information signal from a computer 22 that is communicably connected to the apparatus main body A to execute an image forming operation.

  As described above, the developing device 4 can be applied on the photosensitive drum 1 by adhering toner having a predetermined charge, which is coated and carried around the developing roller 41, to the electrostatic image on the photosensitive drum 1. Form a visual image. At this time, the image can be shaded by controlling the amount of toner deposited on the photosensitive drum 1.

  As a method for controlling the amount of toner deposited on the photosensitive drum 1, for example, a potential difference between the photosensitive drum 1 and the toner can be used. That is, by controlling the exposure amount, the image portion potential of the latent image on the photosensitive drum 1 is controlled, thereby controlling the potential difference with the developing roller 41 to which the developing bias is applied. The amount of toner adhering to the image portion of the electrostatic image can be controlled.

  Furthermore, the developing roller 41 is rotated so that the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1, that is, the ratio Vr / Vd of the developing roller 41 to the peripheral speed Vd of the photosensitive drum 1 becomes a predetermined value. By doing so, development can be performed efficiently.

  By the way, the performance of the toner in the developing device 4 is difficult to maintain from a new state until the toner is exhausted after repeated printing, and usually deteriorates as the printing is repeated. The toner deterioration usually worsens in proportion to a decrease in the amount of toner remaining in the developing device 4.

  However, in the case where a low print ratio, for example, when the ratio of the total print area to the total area of the print surface is defined as the print ratio, a large amount of images having a toner amount of 2% or less is output, the developer 4 Even if a large amount of toner remains, the developing roller 41 rotates for the number of printed sheets, and the toner deteriorates.

  When the toner deteriorates, the amount of toner that does not become a desired charge increases. Therefore, when the latent image is made visible, the amount of toner attached to the photosensitive drum 1 is different from the desired amount. For this reason, for example, there may be a problem of deterioration in image quality such as strangeness of image density.

  That is, the latter half of the life of the process cartridge B, the time when the developer is almost exhausted, or the fact that the developer roller 41 has rotated a lot despite the fact that a large amount of developer remains due to the main output of low print output, etc. Due to the deterioration of the developer, there may be a problem that the image quality deteriorates.

  Therefore, by changing the peripheral speed Vr of the developing roller 41 with respect to the peripheral speed Vd of the photosensitive drum 1, that is, the peripheral speed ratio Vr / Vd of the developing roller 41 with respect to the photosensitive drum 1 is optimized according to the deterioration state of the toner. This solves the problem as described above.

  In this embodiment, drive sources (first and second drive sources 13 and 14) for independently driving the photosensitive drum 1 and the developing roller 41 are provided individually. Then, the peripheral speed ratio of the developing roller 41 to the photosensitive drum 1 is changed by changing the peripheral speed of the developing roller 41 while maintaining the process speed (that is, the peripheral speed of the photosensitive drum 1 remains constant).

  In general, when the toner deteriorates, the amount of toner adhering to the photosensitive drum 1 is smaller than the desired amount, and as a result, when the image has a low density, the peripheral speed Vr of the developing roller 41 is increased, The peripheral speed ratio Vr / Vd is increased so that a desired image density is obtained. As described above, even when the toner is deteriorated, the optimum peripheral speed Vr of the developing roller 41 is always set so that the image density does not fluctuate.

  The peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 is changed based on the durability information of the process cartridge B.

  More specifically, in this embodiment, in order to calculate the optimum peripheral speed Vr of the developing roller 41, information stored in the storage elements 21 provided in the process cartridge B is used. The storage element 21 is electrically connected to the controller unit 11 provided in the apparatus main body A by attaching the process cartridge B to the apparatus main body A, and exchanges information between the controller unit 11 and the storage element 21. Can be done.

  The storage element 21 stores at least durability information of the process cartridge B as various information regarding the process cartridge B. More specifically, the endurance information of the process cartridge B is information regarding the use state of the process cartridge B, and is information proportional to the use amount of the process cartridge B. It is information which shows the value of the index which changes as a result. As the durability information of the process cartridge B, the cumulative rotational speed of the photosensitive drum 1 and the cumulative rotational speed of the developing roller 41 can be preferably used.

  Here, the information on the remaining amount of the developer in the developing device 4 itself is not proportional to the usage amount of the process cartridge B. That is, the change rate of the remaining amount of the developer according to the amount of use of the process cartridge B differs between when a large number of images with a high print ratio are output and when a large number of images with a low print ratio are output. Therefore, the information on the remaining amount of the developer in the developing device 4 alone does not become the durability information of the process cartridge B. However, in the present invention, the remaining amount information of the developer in the developing device 4 is used together with other durability information of the process cartridge B, for example, for controlling the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1. Is not to be excluded.

  In this embodiment, the storage element 21 stores at least the cumulative number of rotations of the developing roller 41 as the durability information of the process cartridge B. The number of rotations of the developing roller 41 is measured according to the time during which the roller is rotated, and is accumulated and stored in the storage element 21 each time one image is output, or one job (single or A series of image forming operations for a plurality of transfer materials) can be accumulated in the storage element 21 and stored.

  Then, the accumulated rotational speed of the developing roller 41 stored in the storage element 21 is compared with a predetermined value (threshold value), the peripheral speed of the developing roller 41 is changed with the threshold value as a boundary, and the developing roller 41 and the photosensitive drum 1 are changed. Change the peripheral speed ratio. This threshold value can be set as appropriate so that a reduction in image quality due to toner deterioration can be sufficiently reduced.

  In this embodiment, in order to calculate the optimum peripheral speed of the developing roller 41, the cumulative rotational speed at that time with respect to the assumed total rotational speed is compared with respect to the rotational speed of the developing roller 41.

  In other words, the number of rotations of the developing roller 22 when the process cartridge B reaches the end of its life (set by the exhaustion of toner, the life of the photosensitive drum 1, etc.) The number of rotations is preset. Information on the assumed total number of rotations is stored in advance in the controller unit 11 of the apparatus main body A. Alternatively, the information on the assumed total number of revolutions can be stored in the storage element 21 of the process cartridge B. In this case, more appropriate control can be performed according to each process cartridge B.

  At the time of image formation, the controller unit 11 reads the accumulated rotational speed of the developing roller 41 at that time stored in the storage element 21 of the process cartridge B. Then, the peripheral speed of the developing roller 41 is changed when the cumulative number of rotations of the developing roller 41 at that time exceeds the assumed total number of rotations. That is, that the cumulative number of rotations of the developing roller 41 at that time exceeds the assumed total number of rotations means that many jobs with a low printing ratio are performed by the process cartridge B, It is assumed that the image density varies due to toner deterioration. Accordingly, the peripheral speed Vr of the developing roller 41 is increased when the cumulative rotational speed of the developing roller 41 exceeds the assumed total rotational speed. As a result, the toner that adheres to the electrostatic image on the photosensitive drum 1 is increased by increasing the peripheral speed ratio Vr / Vd between the developing roller 41 and the photosensitive drum 1 for the toner that is difficult to have a desired charge due to deterioration. The amount is set as a desired amount, and the shade of the image is appropriate.

  More specifically, in this embodiment, the number of rotations of the developing roller 41 assumed until the toner in the process cartridge B is exhausted by repeating image formation at a printing ratio of 4% is set as the assumed total number of rotations. .

  While the cumulative number of rotations of the developing roller 41 is equal to or less than the assumed total number of rotations, the peripheral speed ratio Vr / Vd between the developing roller 41 and the photosensitive drum 1 is kept at the initial value.

On the other hand, when the cumulative total number of rotations of the developing roller 41 is exceeded, the peripheral speed of the developing roller 41 is changed to Vr ′ (> Vr), and the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 is
Vr ′ / Vd = 1.1 × Vr / Vd
To be.

  With such a configuration, it is possible to select an appropriate development condition in accordance with not only the remaining amount of toner in the developing device 4 but also the deterioration of the toner. Therefore, good image quality can be maintained until the process cartridge B is replaced.

  FIG. 5 shows a schematic control flow of the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 in this embodiment. First, a print job is sent to the controller unit 11 provided in the apparatus main body A (step 1). The controller unit 11 reads information on the cumulative number of rotations of the developing roller 41 at that time from the storage element 21 included in the process cartridge B (step 2). The controller unit 11 compares the read cumulative rotational speed Rs of the developing roller 41 with the assumed total rotational speed Rt stored in the controller unit 11 (step 3). When it is determined in step 3 that the cumulative rotation speed Rs of the developing roller 41 is equal to or less than the assumed total rotation speed Rt, the controller unit 11 uses the second drive source to rotate the developing roller 41 at the standard peripheral speed Vr. A control signal is output to 16 (step 4). On the other hand, when it is determined in step 3 that the cumulative rotation speed Rs of the developing roller 41 exceeds the assumed total rotation speed Rt, the controller unit 11 rotates the developing roller 41 at the peripheral speed Vr ′ (> Vr). Thus, a control signal is output to the second drive source 16 so that the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 is Vr ′ / Vd = 1.1 × Vr / Vd (step 5).

  Image development is performed by driving the developing roller 41 at the peripheral speed thus controlled (step 6), and the image forming operation is terminated (step 7).

  The above-described control is performed on the process cartridge B for each color. As a result, it is possible to determine the deterioration state of the toner for the process cartridge B of each color, and to drive the developing roller 41 at an appropriate peripheral speed.

  In the above description, the peripheral speed of the developing roller 41 is changed as a threshold value of the durability information of the process cartridge B with respect to one preset assumed total rotation speed as a boundary. However, the present invention is not limited to this. Alternatively, a plurality of durability information threshold values for the process cartridge B may be provided, and the peripheral speed of the developing roller 41 may be changed (that is, changed sequentially) with each threshold value as a boundary.

For example, the achievement rate of the cumulative rotation speed of the developing roller 41 with respect to the assumed total rotation speed, that is,
Achievement rate = (cumulative rotational speed Rs / assumed total rotational speed Rt) × 100 (%)
And the optimum value of the peripheral speed of the developing roller is calculated according to the calculated achievement rate. From this information, it can be determined how much toner in the process cartridge B has deteriorated up to that point. As a result, the developing roller 41 is driven at an optimum peripheral speed in accordance with the deterioration state of the toner. In this case, the achievement rate itself may be stored as the durability information of the process cartridge B, and the predetermined threshold value of the durability information of the process cartridge B is represented by the achievement rate. However, instead of calculating the achievement rate, a plurality of threshold values for the number of rotations of the developing roller 41 may be set in the same manner as the above-mentioned assumed total number of rotations, and the control action using these information is substantially the same. The same.

More specifically, the optimum peripheral speed of the developing roller 41 is set in advance with respect to the achievement rate of the cumulative rotational speed of the developing roller 41 with respect to the assumed total rotational speed. For example, when the achievement rate is less than 100%, the developing roller 41 is driven at the standard peripheral speed Vr. In the case where the achievement rate is 100% or more and less than 150%, 150% or more and less than 200%, or 200% or more, the peripheral speeds of the developing roller 41 are Vr′1, Vr′2, Vr′3 (Vr <Vr′1), respectively. <Vr′2 <Vr′3). As a result, the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 is less than the standard Vr / Vd.
Vr′1 / Vd = 1.1 × Vr / Vd
Vr′2 / Vd = 1.125 × Vr / Vd
Vr′3 / Vd = 1.15 × Vr / Vd
To be. Information on the relationship between the achievement rate of the cumulative rotational speed with respect to the assumed total rotational speed of the developing roller 41 and the optimal rotational speed of the developing roller 41 is stored in the controller unit 11 in advance. Alternatively, this information can be stored in the storage element 21 of the process cartridge B. In this case, more appropriate control can be performed according to each process cartridge.

  Referring to FIG. 6, in this case, first, a print job is sent to the controller unit 11 provided in the apparatus main body A (step 1). The controller unit 11 reads information on the cumulative number of rotations of the developing roller 41 at that time from the storage element 21 included in the process cartridge B (step 2). Next, the controller unit 11 calculates an achievement rate of the read cumulative rotation number Rs of the developing roller 41 with respect to the assumed total rotation number Rt stored in the controller unit 11 (step 3). The controller unit 11 obtains the optimum peripheral speed of the developing roller 41 corresponding to the achievement rate calculated in Step 3 from the relationship between the achievement rate stored in the controller unit 11 and the peripheral speed of the developing roller 41. (Step 4). Next, the controller unit 11 outputs a control signal to the second drive source 16 in order to rotate the developing roller 41 at the peripheral speed obtained in step 4 (step 5).

  Image development is performed by driving the developing roller 41 at the peripheral speed thus controlled (step 6), and the image forming operation is terminated (step 7).

  The above-described control is performed on the process cartridge B for each color. As a result, it is possible to determine the deterioration state of the toner for the process cartridge B of each color, and to drive the developing roller 41 at an appropriate peripheral speed.

  As described above, according to the present embodiment, it is difficult to control the peripheral speed of the developing roller 41 based only on the remaining amount of toner in the process cartridge B, and the use status of the process cartridge B is determined by determining the toner deterioration status. Therefore, it is possible to obtain a high-quality output image that satisfies the image density required for the print job. In particular, in the color image forming apparatus, an appropriate peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 can be achieved with respect to the process cartridge B for each color, so that the influence of image density fluctuation due to toner deterioration is superimposed. Even during easy color image formation, a high-quality image can always be obtained. Further, for example, by changing the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 with a plurality of threshold values of the durability information of the process cartridge B as a boundary, an optimum developing roller according to the deterioration state of the toner can be obtained. Image formation can be performed at a peripheral speed ratio with respect to the photosensitive drum 1.

Example 2
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Accordingly, elements having substantially the same or corresponding functions and configurations as those of the image forming apparatus according to the first exemplary embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, the controller unit 11 calculates the job pixel count, that is, the integrated value of the density level for each pixel, every time a print job is received. The controller unit 11 calculates the print ratio of the job from the pixel count value.

  In the present embodiment, the controller unit 11 calculates the pixel count of the image for each color, and calculates the print ratio for each color in the job. The calculated pixel count and job print ratio are stored in the controller unit 11.

  In this embodiment, the durability information of the process cartridge B and the pixel count recorded in the apparatus main body A are associated with each other, and the optimum peripheral speed of the developing roller 41 is controlled.

  That is, when the print ratio of the job is a high print ratio, for example, 10% or more, the actual density tends to be lower than the desired density. Therefore, it is effective to increase the peripheral speed ratio of the developing roller 41 and the photosensitive drum 1 by increasing the peripheral speed of the developing roller 41. Therefore, in this embodiment, the peripheral speed of the developing roller 41 is set according to the achievement rate of the cumulative rotation number of the developing roller 41 with respect to the assumed total rotation number, and the job with a high printing ratio is set for the same achievement rate. Increases the peripheral speed of the developing roller 41 and increases the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1.

  For example, in this embodiment, for a job with a print ratio of less than 10% as the predetermined threshold for the print ratio of the job, the developing roller 41 is driven at the standard peripheral speed Vr if the achievement rate is less than 100%. In the case where the achievement rate is 100% or more and less than 150%, 150% or more and less than 200%, or 200% or more, the peripheral speed of the developing roller 41 is set to Vr′1 and Vr ′, respectively, as described in the first embodiment. 2, Vr′3 (Vr <Vr′1 <Vr′2 <Vr′3).

  On the other hand, in a job with a printing ratio of 10% or more, the peripheral speed of each developing roller 41 in the job with the printing ratio of less than 10% is multiplied by 1.1. Of course, the peripheral speed of the developing roller 41 can be appropriately set according to the print ratio of the job, and the relationship between the print ratio of the job and the peripheral speed between the developing roller 41 can be set with a finer or coarser step size. Good.

  FIG. 7 shows a schematic control flow of the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 in this embodiment. First, a print job is sent to the controller unit 11 provided in the apparatus main body A (step 1). At this time, the controller unit 11 in the apparatus main body A calculates the pixel count of the sent job and calculates the print ratio of the job (step 2). Further, the controller unit 11 reads out information on the cumulative number of rotations of the developing roller 41 at that time from the storage element 21 included in the process cartridge B (step 3). Next, the controller unit 11 calculates an achievement rate of the read cumulative rotation number Rs of the developing roller 41 with respect to the assumed total rotation number Rt stored in the controller unit 11 (step 4). Then, the controller unit 11 obtains the optimum peripheral speed of the developing roller 41 corresponding to the achievement rate calculated in Step 4 from the relationship between the achievement rate stored in the controller unit 11 and the peripheral speed of the developing roller 41. (Step 5). Next, the controller unit 11 determines whether the job has a normal printing ratio or a high printing ratio (10% or more in the present embodiment) (step 6). If it is determined in step 6 that the print ratio of the job is less than 10%, the controller unit 11 controls the second drive source 16 to rotate the developing roller 41 at the peripheral speed obtained in step 5. A signal is output (step 7). On the other hand, if it is determined in step 6 that the print ratio of the job is 10% or more, the controller unit 11 calculates the peripheral speed of the developing roller 41 at the high print ratio from the peripheral speed obtained in step 5. (In this embodiment, the peripheral speed obtained in step 5 is multiplied by 1.1) (step 8). Then, a control signal is output to the second drive source 16 to rotate the developing roller 41 at the peripheral speed obtained in step 8 (step 9).

  Image development is performed by driving the developing roller 41 at the peripheral speed thus controlled (step 10), and the image forming operation is terminated (step 11).

  The above-described control is performed on the process cartridge B for each color. As a result, it is possible to determine the deterioration state of the toner for the process cartridge B of each color, and to drive the developing roller 41 at an appropriate peripheral speed.

  As described above, according to the present embodiment, in addition to the deterioration state of the toner, the print ratio of the job is also taken into consideration, so that the peripheral between the developing roller 41 and the photosensitive drum 1 can be further optimized according to the use state of the process cartridge B. Image formation can be performed by the speed ratio.

Example 3
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Accordingly, elements having substantially the same or corresponding functions and configurations as those of the image forming apparatus according to the first exemplary embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, as shown in the schematic block diagram of FIG. 8, the apparatus main body A is provided with an environment detection sensor 20 as an environment detection unit that detects information about the environment where the image forming apparatus 100 is placed. Yes. The environmental sensor 20 is electrically connected to the controller unit 11. In this embodiment, the environment sensor 20 inputs a signal indicating the detection result of the ambient temperature and humidity of the image forming apparatus 100 to the controller unit 11.

  In this embodiment, the durability information of the process cartridge B and the temperature / humidity information detected by the environment sensor 20 are associated with each other, and the peripheral speed of the developing roller 41 is controlled to be optimum.

  That is, the image density tends to decrease in a high temperature and high humidity environment, for example, in an environment where the temperature is 27 ° C. or higher and the humidity is 70% RH or higher. Therefore, in a high temperature and high humidity environment, it is effective to increase the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 by increasing the peripheral speed of the developing roller 41. Therefore, in this embodiment, the peripheral speed of the developing roller 41 is set according to the achievement rate of the cumulative rotation number of the developing roller 41 with respect to the assumed total rotation number, and for the same achievement rate, in a high temperature and high humidity environment. Then, the peripheral speed of the developing roller 41 is increased to increase the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1.

  For example, in this embodiment, the developing roller 41 is driven at the standard peripheral speed Vr under a normal environment (other than the following high temperature and high humidity environment) when the achievement rate is less than 100%. In the case where the achievement rate is 100% or more and less than 150%, 150% or more and less than 200%, or 200% or more, the peripheral speed of the developing roller 41 is set to Vr′1 and Vr, respectively, as described in the first embodiment. '2, Vr'3 (Vr <Vr'1 <Vr'2 <Vr'3).

  On the other hand, as a predetermined threshold value of the environmental temperature and humidity, in a high temperature and high humidity environment where the temperature is 27 ° C. or higher and the humidity is 70% RH or higher, the peripheral speed of each developing roller 41 in the normal environment is multiplied by 1.05.

  FIG. 9 shows a schematic control flow of the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 in this embodiment. First, a print job is sent to the controller unit 11 provided in the apparatus main body A (step 1). Next, the controller unit 11 reads information on the cumulative number of rotations of the developing roller 41 at that time from the storage element 21 included in the process cartridge B (step 2). The controller unit 11 calculates the achievement rate of the accumulated rotational speed Rs of the read developing roller 41 with respect to the assumed total rotational speed Rt stored in the controller unit 11 (step 3). The controller unit 11 obtains the optimum peripheral speed of the developing roller 41 corresponding to the achievement rate calculated in Step 3 from the relationship between the achievement rate stored in the controller unit 11 and the peripheral speed of the developing roller 41. (Step 4). Next, the controller unit 11 reads environmental temperature / humidity information from the environmental sensor 20 (step 5). The controller unit 11 determines whether or not the environment is a high temperature and high humidity environment (step 6). If it is determined in step 6 that the environment is not a high-temperature and high-humidity environment, the controller unit 11 outputs a control signal to the second drive source 16 in order to rotate the developing roller 41 at the peripheral speed obtained in step 4. (Step 7). On the other hand, if it is determined in step 6 that the environment is a high-temperature and high-humidity environment, the controller unit 11 calculates the peripheral speed of the developing roller 41 in the high-temperature and high-humidity environment from the peripheral speed obtained in step 4 (this book In the embodiment, the peripheral speed obtained in Step 4 is multiplied by 1.05) (Step 8). Then, a control signal is output to the second drive source 16 to rotate the developing roller 41 at the peripheral speed obtained in step 8 (step 9).

  Image development is performed by driving the developing roller 41 at the peripheral speed thus controlled (step 10), and the image forming operation is terminated (step 11).

  The above-described control is performed on the process cartridge B for each color. As a result, it is possible to determine the deterioration state of the toner for the process cartridge B of each color, and to drive the developing roller 41 at an appropriate peripheral speed.

  As described above, according to the present exemplary embodiment, the image density required for the print job is satisfied without being affected by the toner deterioration state or the environmental change by taking into account the environmental information in addition to the toner deterioration state. High quality images can be obtained.

Example 4
In the second and third embodiments, the control of the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 in consideration of the print ratio information of the job and the environmental information in addition to the durability information of the process cartridge B will be described. did. In addition to the durability information of the process cartridge B, the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 may be controlled in consideration of both the print ratio information and the environment information of these jobs.

  As shown in FIG. 10, first, a print job is sent to the controller unit 11 provided in the apparatus main body A (step 1). At this time, the controller unit 11 in the apparatus main body A calculates the pixel count of the sent job and calculates the print ratio of the job (step 2). Further, the controller unit 11 reads out information on the cumulative number of rotations of the developing roller 41 at that time from the storage element 21 included in the process cartridge B (step 3). Next, the controller unit 11 calculates an achievement rate of the read cumulative rotation number Rs of the developing roller 41 with respect to the assumed total rotation number Rt stored in the controller unit 11 (step 4). Further, the controller unit 11 reads the environmental temperature / humidity information from the environmental sensor 20 (step 5). Then, the controller unit 11 obtains the peripheral speed of the developing roller 41 from the relationship between the achievement rate stored in the controller unit 11 and the peripheral speed of the developing roller 41, and whether the job is a normal print ratio as in the second embodiment. The optimum peripheral speed of the developing roller is calculated depending on whether the printing ratio is high (10% or more in the present embodiment) and whether the environment is a high temperature and high humidity environment as in the third embodiment (step 6). Then, a control signal is output to the second drive source 16 to rotate the developing roller 41 at the peripheral speed obtained in step 8 (step 7).

  The developing roller 41 is driven at the peripheral speed thus controlled to form an image (step 8), and the image forming operation is terminated (step 9).

  In this manner, the print ratio is calculated by determining the deterioration state of the toner from the cumulative number of rotations of the developing roller 41, obtaining environmental information from the output of the environmental sensor 20, and calculating the pixel count of the print job. To do. Then, by calculating the above information, the optimum peripheral speed ratio of the developing roller 41 with respect to the photosensitive drum 1 is calculated, and by controlling the peripheral speed of the developing roller 41, it is always obtained regardless of the durability of the process cartridge B. It becomes easy to obtain a high-quality output image that satisfies the image density.

-Other examples-
In addition to (i) job print ratio information and (ii) environment information described in the above embodiments, (iii) temperature in the apparatus main body A in the case of continuous printing in which a job prints a plurality of sheets at once. Change information, (iv) information on the cumulative number of printed sheets of the apparatus main body A, and (v) information on the type of transfer material S, basis weight, smoothness, etc. can be used alone or in combination with other information. By calculating in consideration of the durability information, the peripheral speed of the developing roller 41 can be calculated, and the optimal peripheral speed ratio Vr / Vd between the developing roller 41 and the photosensitive drum 1 can be determined. Thereby, it is possible to easily maintain a stable and high-quality image.

  That is, as the temperature in the apparatus main body A increases, the concentration tends to decrease. Therefore, during continuous printing, it is effective to increase the peripheral speed of the developing roller 41 and increase the peripheral speed ratio (Vr / Vd) between the developing roller 41 and the photosensitive drum 1 as the temperature in the apparatus main body A increases. It is.

  Also, depending on the type, weighing and smoothness of the transfer material S, the transfer efficiency may change and the density may change. Therefore, for example, when the type of the transfer material S is a film, when the weighing is large, or when the smoothness is rough, the peripheral speed of the developing roller 41 is increased, and the peripheral speed ratio between the developing roller 41 and the photosensitive drum 1 is increased. It is effective to increase (Vr / Vd).

  Further, as the cumulative number of printed sheets of the apparatus main body A increases, the transfer efficiency tends to decrease. Therefore, it is effective to increase the peripheral speed of the developing roller 41 and increase the peripheral speed ratio (Vr / Vd) between the developing roller 41 and the photosensitive drum 1 as the cumulative number of printed sheets of the apparatus main body A increases. is there.

  Furthermore, by adding information on calibration periodically performed according to the number of printed sheets, the peripheral speed ratio Vr / Vd can be determined more accurately, so that a high-quality output image can always be maintained. That is, it can be realized by determining whether a desired density is obtained from the calibration result and changing the peripheral speed of the developing roller as one means for optimizing the developing conditions.

  In each of the above embodiments, the accumulated rotation speed information of the developing roller 41 is used as the durability information of the process cartridge B. However, instead of or in addition to this, the accumulated rotation speed information of the photosensitive drum 1 may be used. Also in this case, as in the above-described embodiment, the number of rotations of the photosensitive drum 1 when the process cartridge B reaches the end of its life is set by repeating a job with an average printing ratio, and this is set as the assumed total number of rotations. It can be used as a threshold value for the durability information of B, or for calculating the achievement rate of the cumulative number of rotations of the photosensitive drum 1 with respect to the assumed total number of rotations. Further, in place of or in addition to one or both of the cumulative rotation speed information of the developing roller 41 and the photosensitive drum 1, as the durability information of the process cartridge B, the cumulative number of printed sheets (image output number) by the process cartridge B is used. It can also be used. Furthermore, instead of the number of rotations (amount) of the developing roller or photosensitive drum, the number of printed sheets (amount), etc., corresponding time information may be used, which are substantially the same information.

  In each of the above embodiments, in order to change the peripheral speed ratio Vr / Vd, driving means capable of independently controlling the peripheral speeds of the developing roller 41 and the photosensitive drum 1 are the developing roller 41 and the photosensitive drum 1. And an independent drive source for driving each of them. The present invention is not limited to this, and the same effect can be obtained by providing a speed change mechanism in the drive train. In this case, since the number of drive sources can be reduced, the effect of suppressing the size and cost of the image forming apparatus can also be achieved.

  Further, in the above-described embodiments, the image forming apparatus is described as a color image forming apparatus using a conveyance belt, but the present invention is not limited to this. As is well known to those skilled in the art, a toner image composed of, for example, a plurality of color toners is superimposed and transferred (primary transfer) onto an intermediate transfer member, and then the toner image is transferred (secondary transfer) to a transfer material. There is an image forming apparatus that forms a color image. In this case, a plurality of developing devices using different color toners are provided for a single photosensitive member, and toner images sequentially formed on the photosensitive member by the plurality of developing devices are sequentially transferred to the intermediate transfer member, Alternatively, as in the above-described embodiments, there are toners that sequentially transfer toner images formed by a plurality of image forming units onto an intermediate transfer member. The present invention is equally applicable to image forming apparatuses using these intermediate transfer members. Of course, the present invention is also effective for a monochrome image forming apparatus. Further, the image carrier is not limited to the photosensitive drum, and may be a photosensitive belt.

1 is a cross-sectional view of an embodiment of an image forming apparatus to which the present invention can be applied. FIG. 2 is a schematic cross-sectional view of a process cartridge that can be attached to and detached from the image forming apparatus of FIG. 1. FIG. 3 is an external view of the process cartridge of FIG. 2. It is a schematic control block diagram which shows one control aspect of the peripheral speed ratio control method of the developing roller and photosensitive drum according to this invention. It is a flowchart for demonstrating one Example of the peripheral speed ratio control of the developing roller and photosensitive drum according to this invention. It is a flowchart for demonstrating the other Example of the peripheral speed ratio control of the developing roller and photosensitive drum according to this invention. It is a flowchart for demonstrating the other Example of the peripheral speed ratio control of the developing roller and photosensitive drum according to this invention. It is a general | schematic control block diagram which shows the other control aspect of the peripheral speed ratio control method of the developing roller and photosensitive drum according to this invention. It is a flowchart for demonstrating the other Example of the peripheral speed ratio control of the developing roller and photosensitive drum according to this invention. It is a flowchart for demonstrating the other Example of the peripheral speed ratio control of the developing roller and photosensitive drum according to this invention.

Explanation of symbols

1 Photosensitive drum (image carrier)
4 Developing Device 13 First Drive Source 16 Second Drive Source 21 Storage Element 41 Developing Roller (Developer Carrier)
100 Image forming apparatus A Image forming apparatus body B Process cartridge

Claims (18)

A rotatable image carrier for carrying an image by a developer;
A developing device comprising: a container for storing the developer; and a developer carrier that rotates to convey the developer in the container and supply the developer to the image carrier;
Drive means for variably controlling the ratio of the peripheral speed of the developer carrier to the peripheral speed of the image carrier;
Have
In the image forming apparatus in which the cartridge including at least the developing device is detachable from the apparatus main body,
An image forming apparatus, wherein a peripheral speed ratio between the developer carrier and the image carrier is changed according to durability information of the cartridge.   The image forming apparatus according to claim 1, wherein the peripheral speed ratio is changed by changing a peripheral speed of the developer carrier.   3. The image forming apparatus according to claim 1, wherein the driving unit includes separate driving sources for independently driving the developer carrier and the image carrier. 4.   4. The image forming apparatus according to claim 1, wherein the durability information of the cartridge indicates an index value that changes substantially in proportion to the amount of use of the cartridge.   5. The cartridge cartridge according to claim 1, wherein the durability information of the cartridge includes at least one of a cumulative rotation speed of the developer carrier, a cumulative rotation speed of the image carrier, and an image output number. The image forming apparatus described in the item.   6. The image forming apparatus according to claim 1, further comprising storage means for storing durability information of the cartridge.   The image forming apparatus according to claim 6, wherein the storage unit is attached to the cartridge.   The image forming apparatus according to claim 1, wherein the peripheral speed ratio is changed with a predetermined threshold value of durability information of the cartridge as a boundary.   After the cumulative rotation speed of the developer carrier reaches before reaching a predetermined threshold, the peripheral speed of the developer carrier is represented by Vr, and the peripheral speed of the image carrier is represented by Vr / Vd. The image forming apparatus according to claim 8, wherein the peripheral speed ratio is increased.   The image forming apparatus according to claim 8 or 9, wherein a plurality of predetermined threshold values of the life information of the cartridge are set.   The peripheral speed ratio is changed according to a print ratio of an output image in a series of image output operations started by a single image output start instruction. The image forming apparatus described in 1.   12. The image forming apparatus according to claim 11, wherein the print ratio is calculated from a pixel count.   The image forming apparatus according to claim 11, wherein the peripheral speed ratio is changed with a predetermined threshold of the print ratio as a boundary.   When the value indicated by the endurance information of the cartridge is the same, the peripheral speed of the developer carrying member is Vr and the image when the printing ratio exceeds the predetermined threshold value than when the printing ratio is equal to or lower than the predetermined threshold value. 14. The image forming apparatus according to claim 13, wherein the peripheral speed ratio expressed by Vr / Vd is increased with the peripheral speed of the carrier being Vd.   The image forming apparatus according to claim 1, wherein the peripheral speed ratio is changed according to environmental information.   16. The image forming apparatus according to claim 15, wherein the peripheral speed ratio is changed with a predetermined threshold value of the environmental information as a boundary.   When the values indicated by the endurance information of the cartridge are the same, when the temperature and humidity indicated by the environmental information exceed the predetermined threshold values, the circumference of the developer carrier is exceeded. 17. The image forming apparatus according to claim 15, wherein the peripheral speed ratio expressed by Vr / Vd is increased, where Vr is a speed and a peripheral speed of the image carrier is Vd.   The image forming apparatus according to claim 1, wherein the cartridge is a process cartridge in which the image carrier is also detachably attached to the apparatus main body.

Images