JP2016218422A - Image formation apparatus and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a problem in which a developer accumulated on the upstream side at the position opposite to an image carrier and a development roller sticks to the development roller and the image carrier by entering at once so as to be brought into pressure-contact with the opposite position thereof when the image carrier is rotationally driven in addition to the development roller after control even in a case of performing the control of rotationally driving the development roller in the state where the rotational driving of the image carrier is stopped.SOLUTION: In a case where the first driving mode for performing control so as to rotationally drive a development roller 13a in the state where the rotational driving of a photoreceptor drum 12 (image carrier) is stopped at the time of non-image formation, the second driving mode for performing control so that a linear velocity ratio X (ratio B/A of a linear velocity B of the development roller 13a to a linear velocity A of the photoreceptor drum 12 in a development gap) at the time when the rotational driving of the photoreceptor drum 12 is started in addition to the rotational driving of the development roller 13a becomes smaller than 1 is executed for a prescribed time D2.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus using an electrophotographic method such as a copying machine, a printer, a facsimile, or a multifunction machine thereof, and a process cartridge that is detachably installed therein.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a two-component developer (additive) composed of toner and a carrier is driven while a developing device in an empty state (or a state close thereto) is driven during non-image formation. In other words, there is known a technique for replenishing the inside of a developing device with a developer such as, for example, Patent Documents 1 and 2).

Specifically, in Patent Document 1, when a developer preset case containing a new developer is installed on top of a new developing device and the developing device is started to be used, the developing device and the photosensitive drum (image) are disclosed. A technique for replenishing the developer uniformly from the developer preset case to the inside of the developing device while driving the carrier) is disclosed.
Further, in Patent Document 2, with respect to a new developing device attached to the image forming apparatus or a developing device at the time of changing the developer with the main body cover (developer replenishment cover) of the image forming apparatus opened. A developer container containing a new developer is connected from the outside, and the developer is uniformly replenished from the developer container to the inside of the developing apparatus while driving the developing device and the photosensitive drum (image carrier). Technology is disclosed.

In the conventional image forming apparatus, the developer is replenished inside the developing device while driving the developing device in an empty state (or a state close thereto), so that the operator manually drives the developing device. Compared with the case where the developer is replenished, an effect that the developer can be replenished uniformly in the developing device in a relatively simple and short time can be expected.
However, in the conventional technique, when the developer is replenished, in addition to the developing roller (developing device), the photosensitive drum (image carrier) is also rotationally driven. In some cases, the photosensitive drum, the cleaning blade, or the like may be worn out earlier.

On the other hand, it is conceivable to control so that the rotation of the photosensitive drum is stopped and only the developing roller (developing device) is driven when the developer is replenished. However, in that case, when the developer accumulates on the upstream side of the facing position (development gap) between the photosensitive drum and the developing roller, and then the photosensitive drum is driven to rotate in addition to the developing roller, the photosensitive member There is a possibility that the developer accumulated on the upstream side of the position where the drum and the developing roller face each other is so pressed that the developer is fixed to the developing roller and the photosensitive drum. There is. If the developer adheres to the developing roller or the photosensitive drum in such a manner, a streak image is formed on the image or periodic density unevenness occurs.
In addition, such a problem is not limited to when the developer is replenished, and can occur in common when controlling the rotation of the developing roller while the rotation of the photosensitive drum is stopped. is there.

  The present invention has been made to solve the above-described problems. Even when control is performed to rotate the developing roller while the rotation of the image carrier is stopped, development is performed after the control. When the image carrier is rotated in addition to the roller, the developer accumulated on the upstream side of the position where the image carrier and the developing roller are opposed to each other is pressed so that the developer roller and the image carrier are pressed against each other. It is an object of the present invention to provide an image forming apparatus and a process cartridge that are less likely to cause a problem of being fixed to the body.

  According to a first aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier that is rotationally driven in a predetermined direction by a first driving unit; and a developer that is accommodated therein and that faces the image carrier. The latent image formed on the surface of the image carrier is developed by being rotated in a predetermined direction by the second driving means so that a linear velocity ratio with respect to the linear velocity of the image carrier at the position becomes a predetermined value of 1 or more. A developing device having a developing roller, and the first driving unit and the second driving unit so as to rotationally drive the developing roller in a state in which the rotational driving of the image carrier is stopped during non-image formation. When the first driving mode for controlling the above is executed, the linear velocity ratio when the rotational driving of the image carrier is started in addition to the rotational driving of the developing roller is made smaller than 1. The first drive Second driving mode for controlling the said the stepped second driving means is being performed for a predetermined time.

  According to the present invention, even when the rotation control of the developing roller is performed in a state where the rotation driving of the image carrier is stopped, the image carrier is rotated in addition to the developing roller after the control. Image forming is less likely to cause the developer accumulated on the upstream side of the opposing position between the image carrier and the developing roller to be firmly pressed to the developing roller and the image carrier so that the developer is pressed against the opposing position. An apparatus and a process cartridge can be provided.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. It is a block diagram which shows an image creation part. (A) The schematic sectional view which looked at the upper part of the developing device in the longitudinal direction, (B) The schematic sectional view which looked at the lower part of the developing device in the longitudinal direction. FIG. 6 is a schematic perspective view showing a state where a developer is replenished in a developing device in a black process cartridge. 6 is a timing chart showing control when a developer is replenished with a developer. (A) Schematic diagram in the first drive mode, (B) Schematic diagram in the second drive mode, and (C) Schematic diagram during normal image formation, showing the vicinity of the development gap. FIG. 6 is a schematic diagram showing the vicinity of a development gap when a normal image forming operation is performed without performing the second drive mode after the first drive mode. FIG. 6 is a table showing whether the developer adheres to the surface of the developing roller when the linear velocity of the developing roller and the linear velocity of the photosensitive drum are changed after the first drive mode. It is a graph which shows the change of the drive torque of the developing device after starting a 2nd drive mode. It is a flowchart which shows the control when a developing device is replenished with a developing agent. 9 is a timing chart showing control when the developer is replenished in the developing device and the cleaning blade is new in the image forming apparatus according to Embodiment 2 of the present invention. 10 is a timing chart showing control when the developer is not replenished in the developing device and the cleaning blade is new. 10 is a flowchart showing control in the second embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
A first embodiment of the present invention will be described in detail with reference to FIGS.
First, the overall configuration and operation of the image forming apparatus will be described with reference to FIG.
In FIG. 1, 1 is a tandem color copier as an image forming apparatus, 2 is a writing unit that emits laser light based on input image information, 3 is a document conveying unit that conveys a document D to a document reading unit 4, and 4 is An original reading unit that reads image information of the original D, 7 is a paper feeding unit that accommodates a recording medium P such as transfer paper, 9 is a registration roller (timing roller) that adjusts the conveyance timing of the recording medium P, 10Y, 10M, Reference numerals 10C and 10BK denote process cartridges (image forming units) on which toner images of respective colors (yellow, magenta, cyan, and black) are formed.

  Reference numeral 17 denotes an intermediate transfer belt onto which toner images of a plurality of colors are transferred, 18 denotes a secondary transfer bias roller for transferring the color toner image on the intermediate transfer belt 17 onto the recording medium P, and 19 denotes an intermediate transfer. An intermediate transfer belt cleaning unit 20 for cleaning the belt 17 is a primary transfer bias for transferring the toner images formed on the photosensitive drums 12 of the process cartridges 10Y, 10M, 10C, and 10BK on the intermediate transfer belt 17 in an overlapping manner. A roller, 30 is a fixing device that fixes an unfixed image on the recording medium P, and 50Y, 50M, 50C, and 50BK are toner cartridges (toner containers) that contain toner of each color (yellow, magenta, cyan, black). Show.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described.
Note that FIG. 2 can also be referred to for the image forming process performed on the photosensitive drums 12 of the process cartridges 10Y, 10M, 10C, and 10BK.

First, the document D is transported from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 3 and placed on the contact glass 5 of the document reading unit 4. Then, the document reading unit 4 optically reads the image information of the document D placed on the contact glass 5.
Specifically, the document reading unit 4 scans the image of the document D on the contact glass 5 while irradiating light emitted from an illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. The writing unit 2 emits laser light L (see FIG. 2) based on the image information of each color toward the corresponding photosensitive drum 12.

On the other hand, the photosensitive drums 12 of the four process cartridges 10Y, 10M, 10C, and 10BK are rotated counterclockwise in FIG. First, the surface of the photosensitive drum 12 is uniformly charged at a portion facing the charging device 14 (charging roller) (this is a charging process). Thus, a charged potential is formed on the photosensitive drum 12. Thereafter, the surface of the charged photosensitive drum 12 reaches the irradiation position of each laser beam.
In the writing unit 2, laser light corresponding to the image signal is emitted from the four light sources corresponding to each color. Each laser beam passes through a separate optical path for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

  The laser beam corresponding to the yellow component is applied to the surface of the photosensitive drum 12 of the first process cartridge 10Y from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 12 by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 12 after being charged by the charging device 14.

  Similarly, the laser beam corresponding to the magenta component is irradiated on the surface of the photosensitive drum 12 of the second process cartridge 10M from the left side of the paper, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light is applied to the surface of the photosensitive drum 12 of the third process cartridge 10C from the left side of the drawing, thereby forming an electrostatic latent image of the cyan component. The black component laser light is applied to the surface of the photoconductive drum 12K of the fourth process cartridge 10BK from the left side of the drawing to form an electrostatic latent image of the black component.

Thereafter, the surface of the photosensitive drum 12 on which the electrostatic latent images of the respective colors are formed reaches a position facing the developing device 13 (developing unit). Then, each color toner is supplied from each developing device 13 onto the photosensitive drum 12, and the latent image on the photosensitive drum 12 is developed (this is a developing step).
Thereafter, the surface of the photosensitive drum 12 after the development process reaches a portion facing the intermediate transfer belt 17 (primary transfer nip portion). Here, a primary transfer bias roller 20 is installed at each facing portion so as to abut on the inner peripheral surface of the intermediate transfer belt 17. Then, at the position of the primary transfer bias roller 20 (a primary transfer bias having a polarity different from the toner polarity) is applied, the process cartridges 10Y, 10M, 10C, and 10BK are exposed on the intermediate transfer belt 17. The toner images of the respective colors formed on the body drum 12 are sequentially transferred in a superimposed manner (this is a primary transfer process).

Then, the surface of the photosensitive drum 12 after the transfer process reaches a position facing the cleaning blade 15 (cleaning unit). Then, the untransferred toner remaining on the photosensitive drum 12 is collected by the cleaning blade 15 (cleaning process).
Thereafter, the surface of the photoconductive drum 12 passes through a static elimination unit (not shown), and a series of image forming processes on the photoconductive drum 12 is completed.

On the other hand, the intermediate transfer belt 17 on which the toner images of the respective colors on the photosensitive drums 12 of the process cartridges 10Y, 10M, 10C, and 10BK are transferred (carrying) is run in the clockwise direction in the drawing and is secondary. It reaches a position facing the transfer bias roller 18. Then, a color toner image carried on the intermediate transfer belt 17 is transferred onto the recording medium P at a position facing the secondary transfer bias roller 18 (secondary transfer step).
Thereafter, the surface of the intermediate transfer belt 17 reaches the position of the intermediate transfer belt cleaning unit 19. Then, the untransferred toner adhered on the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit 19, and a series of transfer processes in the intermediate transfer belt 17 is completed.

Here, the recording medium P transported between the intermediate transfer belt 17 and the secondary transfer bias roller 18 (secondary transfer nip) is transported from the paper supply unit 7 via the registration roller 9 and the like. It is a thing.
Specifically, the recording medium P fed by the paper feeding roller 8 from the paper feeding unit 7 that stores the recording medium P is guided to the registration roller 9 after passing through the conveyance guide. The recording medium P that has reached the registration roller 9 is conveyed toward the secondary transfer nip at the same timing.

Then, the recording medium P on which the full color image is transferred is guided to the fixing device 30 by the conveyance belt. In the fixing device 30, the color image is fixed on the recording medium P at the nip between the fixing belt and the pressure roller.
Then, the recording medium P after the fixing step is discharged as an output image outside the apparatus main body 1 by the discharge roller, and a series of image forming processes is completed.

Next, the process cartridge 10 (image forming unit) will be described in detail with reference to FIGS.
As shown in FIG. 2, the process cartridge 10 includes a photosensitive drum 12 as an image carrier, a charging device 14 (charging roller) for charging the photosensitive drum 12, and a latent image formed on the surface of the photosensitive drum 12. A developing device 13 (developing unit) for developing, a cleaning blade 15 (cleaning unit) for removing untransferred toner on the photosensitive drum 12, and a lubricant supplying device 16 (lubricant supplying) for supplying a lubricant onto the photosensitive drum 12 Part), etc. The process cartridge 10 is configured to be detachable (replaceable) from the apparatus main body 1.
Since the process cartridges of the respective colors have almost the same structure, the process cartridges, the photosensitive drums, and the developing devices in FIG. 2, FIG. 3 and the like are excluded from the alphabets (Y, C, M, BK). Illustrated.

Here, the photosensitive drum 12 as an image bearing member is a negatively charged organic photosensitive member, and a photosensitive layer or the like is provided on a drum-shaped conductive support.
Although not shown, the photosensitive drum 12 has an undercoat layer that is an insulating layer, a charge generation layer and a charge transport layer as a photosensitive layer, and a protective layer (surface layer) in this order on a conductive support as a base layer. Are stacked. As the conductive support (base layer) of the photosensitive drum 12, a conductive material having a volume resistance of 10 ¹⁰ Ωcm or less can be used.
The photosensitive drum 12 is rotationally driven in a predetermined direction (counterclockwise in FIG. 2) by a first drive motor 61 as a first drive means. In the first embodiment, a charging device 14 (charging roller), a lubricant supply roller 16a, and a conveying screw 15b, which will be described later, are also shown in FIG. 2 by transmission of driving force from the first driving motor 61 via a gear train. It is rotationally driven in the direction of the arrow shown.

The charging device 14 is a charging roller (roller member) formed by coating an outer periphery of a conductive metal core (shaft portion) with a medium-resistance elastic layer. The charging drum 14 rotates the photosensitive drum 12 with respect to the lubricant supply device 16. It is disposed so as to contact the photosensitive drum 12 on the downstream side in the direction.
A predetermined voltage (charging bias) is applied to the charging device 14 from a power supply unit (not shown) installed in the apparatus main body 1, thereby uniformly charging the surface of the opposing photosensitive drum 12.
In the first embodiment, the charging device 14 is in contact with the photosensitive drum 12, but the charging device 14 may be opposed to the photosensitive drum 12 with a minute gap therebetween.

The cleaning blade 15 (cleaning unit) is disposed on the downstream side in the rotation direction of the photosensitive drum 12 with respect to the lubricant supply device 16. The cleaning blade 15 is made of a rubber material such as urethane rubber, and is in contact with the surface of the photosensitive drum 12 at a predetermined angle and a predetermined pressure. As a result, deposits such as untransferred toner adhering to the photosensitive drum 12 are mechanically scraped and collected in the process cartridge 10. The toner collected in the process cartridge 10 is disposed as a waste toner in a waste toner collection container (not shown, and is detachably installed on the back side of the apparatus main body 1 in FIG. 1 in the direction perpendicular to the paper surface). It is conveyed toward the conveying screw 15b. Here, examples of the adhering material that adheres to the photosensitive drum 12 include paper powder generated from the recording medium P (paper) in addition to the untransferred toner, and a discharge product that is generated on the photosensitive drum 12 when discharged by the charging device 14. And additives added to the toner.
The cleaning blade 15 in the first embodiment also functions as a thinning blade that thins the lubricant supplied onto the photosensitive drum 12 by the lubricant supply roller 16a.

The lubricant supply device 16 (lubricant supply unit) holds the solid lubricant 16b, the lubricant supply roller 16a (brush-shaped roller) that is in sliding contact with the photosensitive drum 12 and the solid lubricant 16b, and the solid lubricant 16b. A compression spring 16c that urges the holding member 16e toward the lubricant supply roller 16a together with the member 16e and the solid lubricant 16b is formed.
The lubricant is supplied onto the photosensitive drum 12 by the lubricant supply device 16 configured as described above. Then, the lubricant supplied onto the photosensitive drum 12 is thinned by the cleaning blade 15 disposed on the downstream side of the lubricant supply device 16.

  2 and 3, in the developing device 13, a developing roller 13a as a developer carrying member is opposed to the photosensitive drum 12 with a small gap (about 0.2 to 0.25 mm). A developing region (developing nip portion) where the photosensitive drum 12 and the magnetic brush are in contact with each other is formed at the opposite position (developing gap). A developer G (two-component developer) composed of toner T and carrier C is accommodated in the developing device 13. The developing device 13 develops the electrostatic latent image formed on the photosensitive drum 12 (forms a toner image). The configuration and operation of the developing device 13 will be described in detail later.

Referring to FIG. 1, toner cartridges 50Y, 50M, 50C, and 50BK (toner containers) contain toner T to be supplied into developing device 13 therein. Specifically, based on the information of the toner concentration (the ratio of the toner T in the developer G) detected by the magnetic sensor 13h (see FIG. 3) installed in the developing device 13, it is not shown. The toner T is appropriately replenished from the toner replenishing port 13e from the corresponding toner cartridge of the four toner cartridges 50Y, 50M, 50C, and 50BK into the developing device 13 through the toner replenishing device.
The replenishment of the toner T is not limited to the toner density information, but is performed based on the image density information detected from the reflectance of the toner image formed on the photosensitive drum 12, the intermediate transfer belt 17, or the like. May be. Further, it may be determined that toner T is replenished by combining these different pieces of information.
Further, as a toner replenishing device for replenishing toner to the developing device 13, a toner replenishing device that transports toner using a transport auger, a device that transports toner with air using a screw pump, and the like are known. Things can be used.
Further, the four toner cartridges 50Y, 50M, 50C, and 50BK are configured so as to be detachable from the apparatus main body from the front side in the vertical direction (the front side in the operation direction) of the apparatus main body 1 in FIG. When the toner in the cartridge runs out, it is replaced with a new one.

Hereinafter, the developing device 13 in the image forming apparatus will be described in detail.
2 and 3, the developing device 13 includes a developing roller 13a as a developer carrier, conveying screws 13b1 and 13b2 (auger screws) as conveying members, a doctor blade 13c as a developer regulating member, and the like. It consists of
An opening is formed in the developing case 13k of the developing device 13 in order to expose a part of the developing roller 13a to the photosensitive drum 12 side. The developing roller 13a includes a sleeve 13a2 formed of a non-magnetic material such as aluminum, stainless steel, brass, or conductive resin in a cylindrical shape, and a second driving motor 62 (gear installed on the sleeve shaft) as second driving means. And a drive gear meshing with each other is installed). In the sleeve 13a2 of the developing roller 13a, a magnet 13a1 that forms a plurality of magnetic poles on the peripheral surface of the sleeve 13a2 is fixed non-rotatingly (the magnet shaft is lightly press-fitted into the side plate). The developer G carried on the developing roller 13a is conveyed as the developing roller 13a (sleeve 13a2) rotates in the direction of the arrow, and reaches the position of the doctor blade 13c (developer regulating member). Then, after the developer G on the developing roller 13a is regulated to an appropriate amount (a pumping amount per unit area is about 30 to 38 mg / cm ² ) at this position, the developer G is opposed to the photosensitive drum 12 ( To the development area). The photosensitive drum is developed by an electric field formed in the developing region (a developing electric field that is a difference between the latent image potential formed on the photosensitive drum 12 and the developing bias applied to the developing roller 13a). The toner is adsorbed to the latent image formed on the surface 12.

  The doctor blade 13c as a developer regulating member is a substantially plate-like member made of a nonmagnetic material, and is disposed so as to face the upper side of the developing roller 13a. In the first embodiment, the facing distance (doctor gap) between the doctor blade 13c and the developing roller 13a is set to about 0.2 to 0.3 mm.

The developing roller 13a is rotationally driven in a predetermined direction (clockwise in FIG. 2) by the second drive motor 62 (second drive means). That is, both the photosensitive drum 12 and the developing roller 13a are rotationally driven so as to move from the upper side to the lower side at the mutually opposing positions (developing gap).
Here, in the first embodiment, the developing roller 13a is synonymous with the linear velocity A (the linear velocity of the outer peripheral surface) of the photosensitive drum 12 at a position facing the photosensitive drum 12 (image carrier), and is 415 mm. The development process is performed by being rotationally driven in a predetermined direction by the second drive motor 62 (second drive means) so that the linear speed ratio X with respect to (/ sec.) Becomes a predetermined value of 1 or more. Specifically, in the first embodiment, the linear velocity B of the developing roller 13a during the developing process (image formation) (the linear velocity at the position facing the photosensitive drum 12, which is synonymous with the linear velocity of the outer peripheral surface). Is set to about 623 mm / sec, and the linear velocity ratio X (= B / A) to the linear velocity A of the photosensitive drum 12 described above is set to about 1.5. As described above, the developing process in which the image quality is good can be performed by causing the developing roller 13a to travel relatively faster than the photosensitive drum 12 in the developing region.

In the first embodiment, two conveying screws 13b1 and 13b2 described later are also rotationally driven in the direction of the arrow shown in FIG. 2 by transmission of driving force from the second drive motor 62 via the gear train.
In the first embodiment, the second drive motor 62 is provided as an independent drive system different from the first drive motor 61. Further, the second drive motor 62 is a variable speed motor, and is configured to be able to vary the rotational speed in two stages in the first embodiment.

The two conveying screws 13b1 and 13b2 (conveying members) allow the developer G accommodated in the developing device 13 to move in the longitudinal direction (the vertical direction in FIG. 2 and the left and right direction in FIG. 3), and the developing roller 13a. In the same direction as the rotation axis direction).
The first transport screw 13b1 as the first transport member is disposed at a position facing the developing roller 13a, and transports the developer G horizontally in the longitudinal direction (rotation axis direction) (see FIG. 3A). At the same time, the developer G is supplied onto the developing roller 13a at the position of the pumping magnetic pole (supply in the direction of the white arrow in FIG. 3A).

The second conveying screw 13b2 as the second conveying member is disposed at a position facing the developing roller 13a at a position below the first conveying screw 13b1. The developer G released from the developing roller 13a (the developer G released from the developing roller 13a by the agent separating magnetic pole after the developing process, which is released in the direction of the white arrow in FIG. 3B). Are transported horizontally in the longitudinal direction (the transport in the right direction indicated by the broken line arrow in FIG. 3B).
Then, the second transport screw 13b2 secondly supplies the developer G circulated from the downstream side of the transport path by the first transport screw 13b1 via the first relay portion 13g to the upstream side of the transport path by the first transport screw 13b1. It conveys via the relay part 13f (it is the conveyance shown by the dashed-dotted arrow of FIG. 3).
The two conveying screws 13b1 and 13b2 are arranged so that the rotation axis is substantially horizontal, like the developing roller 13a and the photosensitive drum 12. Moreover, as for the two conveyance screws 13b1 and 13b2, both have a screw part helically wound around the rotating shaft part.

The conveyance path (first conveyance path) by the first conveyance screw 13b1 and the conveyance path (second conveyance path) by the second conveyance screw 13b2 are isolated from each other by a wall portion.
Referring to FIG. 3, the downstream side of the transport path (second transport path) by the second transport screw 13b2 and the upstream side of the transport path (first transport path) by the first transport screw 13b1 are the second relay unit. It communicates via 13f. The developer G that has reached the downstream side of the second conveyance path by the second conveyance screw 13b2 stays in the vicinity of the second relay portion 13f and rises up, and the first conveyance screw 13b1 makes the first through the second relay portion 13f. It is transported (supplied) to the upstream side of the transport path.
In addition, the downstream side of the conveyance path by the first conveyance screw 13b1 and the upstream side of the conveyance path by the second conveyance screw 13b2 communicate with each other via the first relay portion 13g. Then, the developer G that has not been supplied onto the developing roller 13a in the first conveyance path by the first conveyance screw 13b1 falls by its own weight at the first relay portion 13g and reaches the upstream side of the second conveyance path. become.
In addition, in order to improve the transportability of the developer in the second relay portion 13f (delivery of the developer against the direction of gravity from the second transport path to the first transport path), the second transport screw 13b2 A paddle-shaped portion or a screw portion in which the screw winding direction is formed in the reverse direction can also be provided at a downstream position (a position corresponding to the second relay portion 13f).

  With such a configuration, a circulation path for circulating the developer G in the longitudinal direction in the developing device 13 is formed by the two conveying screws 13b1 and 13b2. That is, when the developing device 13 is operated, the developer G accommodated in the device flows in the direction of the broken arrow in FIG. Thus, the developer G supply path to the developing roller 13a (the first transport path by the first transport screw 13b1) and the developer G recovery path (second transport screw) separated from the developing roller 13a. 13b2), the density deviation of the toner image formed on the photosensitive drum 12 can be reduced.

2 and 3A, in the conveyance path by the first conveyance screw 13b1 (below the first conveyance screw 13b1 and at the upstream side of the first conveyance path). A magnetic sensor 13h (toner concentration detecting means) for detecting the toner concentration of the developer circulating in the apparatus is installed. Based on the toner density information detected by the magnetic sensor 13h, the toner cartridge 50 is directed into the developing device 13 through the toner supply port 13e (located in the vicinity of the second relay portion 13f). Then, new toner T is supplied.
Referring to FIG. 3, the toner replenishing port 13e is located above the upstream side of the conveyance path by the first conveyance screw 13b1 and away from the development area (outside the longitudinal range of the development roller 13a). Is).

  Here, referring to FIGS. 3 and 4, the developing device 13 (process cartridge 10) according to the first embodiment is located above the upstream side of the second transport path by the second transport screw 13b2 and in the developing region. A developer replenishing port 13m for replenishing the developer G in the developing device 13 at a position away from the front side of the image forming apparatus 1 (the side where the main body door 100 in FIG. 4 is installed). It is arranged. The opening of the developer replenishing port 13m is sealed by a cap member (not shown) at a normal time other than when the replenishing operation of the two-component developer G to the developing device 13 is performed.

Then, when the developer G is filled in the empty developing device 13 in which the developer G is not accommodated (or a state close thereto), as shown in FIG. 13 is mounted on the image forming apparatus 1, the main body door 100 (main body cover) is opened around the hinge in the direction of the arrow, and the process cartridges 10 </ b> Y, 10 </ b> M, 10 </ b> C, 10 </ b> BK are exposed and the developer of the developing device 13 is exposed. A funnel 71 (relay member) is connected to the replenishing port 13m from the outside, and a developer container 70 (containing a new developer G) is connected to the funnel 71 from the outside. Then, while driving the developing device 13 (while operating the second drive motor 62), the developer G is replenished (introduced) into the developing device 13 from the developer container 70 via the funnel 71. In this way, by replenishing the developer G from the developer replenishing port 13m while driving the developing device 13, the developer G fed from the developer replenishing port 13m is circulated and conveyed by the two conveying screws 13b1 and 13b2. Therefore, as compared with the case where the operator manually replenishes the developer G while driving the developing device 13, the developer G is replenished to the inside of the developing device 13 easily and in a short time. be able to.
4 illustrates a state in which the developer G is replenished to the black process cartridge 10BK (developing device 13) among the four process cartridges 10Y, 10M, 10C, and 10BK (developing device 13). However, the other process cartridges 10Y, 10M, and 10C (developing devices 13) can be similarly replenished with the developer G.

As described above, when the developer G is replenished to the empty developing device 13, a new developing device 13 (process cartridge) is installed in the image forming apparatus 1 or the existing developing device 13 reaches the end of its life. In some cases, the developer G (carrier C) is discarded and replaced with a new developer G (when the developer is replaced). In particular, when the latter developer is replaced, it is necessary to perform an operation of removing the existing developer G that has reached the end of its life from the existing developing device 13, and such an operation is performed by the existing developing device 13 (process The cartridge 10) can be removed from the image forming apparatus 1 and can be performed manually, or when the developing device 13 is provided with a developer discharge port (connected to a waste container) that can be opened and closed. It can also be performed automatically while driving the developing device with the discharge port opened.
In any case, such a replenishment operation of the developer G is a special operation performed with the main body door 100 opened, unlike a normal image forming operation. A special key input is performed using an operation panel (not shown) of the apparatus 1 and executed.

In the first embodiment, when the developer G is replenished to the developing device 13 as described above, the developing device 13 is driven as described above (while the second drive motor 62 is operating). However, the driving of the photosensitive drum 12 is stopped (the driving of the first driving motor 61 is stopped). That is, when the developer G is replenished, the photosensitive drum 12 is stopped rotating, and only the developing device 13 is driven (only the developing roller 13a and the conveying screws 13b1 and 13b2 are driven to rotate). .
As a result, when the developer G is replenished, the cleaning blade 15 may come into sliding contact with the photosensitive drum 12 and the abnormal sound may be generated, the photosensitive drum 12, the cleaning blade 15, the charging device 14, or the like. It is possible to alleviate the problem that the wear of the wearer is accelerated.
In particular, in the first embodiment, since the replenishment operation of the developer G is performed in a state where the main body door 100 is opened and the inside of the image forming apparatus 1 is exposed, the developing bias applied to the developing roller 13a at the time of image formation. In addition, a high voltage such as a charging bias applied to the charging device 14 is not applied, so that a problem that an operator touches a member to which the high voltage is applied does not occur. If the photosensitive drum 12 is driven to rotate with the developing bias and the charging bias turned off in this way, the toner in the developer G carried on the developing roller 13a becomes a scumming toner on the surface of the photosensitive drum 12. As a result, the toner density of the developer G in the developing device 13 decreases, or the ground toner on the photosensitive drum 12 scatters and the inside of the apparatus becomes dirty with the toner. For this reason as well, stopping the driving of the photosensitive drum 12 when replenishing the developer G has a significant meaning.

Hereinafter, characteristic control executed in the image forming apparatus 1 (process cartridge 10) according to the first exemplary embodiment will be described in detail with reference to FIGS.
Referring to FIG. 5, image forming apparatus 1 according to the first exemplary embodiment performs photosensitive drum 12 during non-image formation (a timing at which a normal image forming process is not performed on photosensitive drum 12). The first drive motor 61 (first drive means) and the second drive motor 62 (second drive means) are controlled so that the developing roller 13a is rotationally driven in a state where the rotational drive of the (image carrier) is stopped. When the “first driving mode” is executed, the linear speed ratio X (the line of the photosensitive drum 12 in the developing gap) when the rotational driving of the photosensitive drum 12 is started in addition to the rotational driving of the developing roller 13a thereafter. The ratio of the linear speed B of the developing roller 13a to the speed A is B / A.) The “second drive mode” for controlling the first drive motor 61 and the second drive motor 62 so that the ratio is smaller than 1 is predetermined. time Only 2 are executed. After the second drive mode is executed, the linear velocity ratio X is returned to a normal value (1.5 in the first embodiment), and process control (adjustment of image forming conditions) is performed. Or a normal image forming operation (printing operation) is performed.

Specifically, in the first embodiment, the “first drive mode” is performed in the process cartridge 10 (the developing device 13 and the photosensitive drum 12) in the image forming apparatus 1 as described above with reference to FIG. This is a “developer replenishment mode” that is executed when the developer G is filled in the developing device 13 in a state where the developer accommodated therein is empty or close to it. In the “first drive mode (developer replenishment mode)”, as shown in FIG. 6A, the rotation of the photosensitive drum 12 is stopped and the developing roller 13a (developing device 13) is driven by the second drive motor 62. ) Is driven to rotate at a normal speed (linear speed or rotation speed when a normal image forming operation is performed). Specifically, the linear velocity B of the developing roller 13a at this time is set to about 623 mm / sec.
At this time (when the first drive mode is executed), as described above, the charging bias is not applied to the charging device 14 (charging roller), and the developing bias is applied to the developing roller 13a. It is controlled so that it is not applied (other biases such as a transfer bias are also turned off).
The time D1 during which the “first drive mode (developer replenishment mode)” is executed is based on the capacity of the developer container 70, the speed at which the developer G is circulated by the conveying screws 13b1 and 13b2 in the developing device 13, and the like. It is set in advance to a constant value (about 30 seconds in the first embodiment).

In the first embodiment, when such a “first drive mode (developer replenishment mode)” is executed, the developing roller 13a is always more immediately after the linear velocity A of the photosensitive drum 12. The “second drive mode” in which the first drive motor 61 and the second drive motor 62 are operated in a state where the linear velocity B ′ is slowed is executed for a predetermined time D2 (about 10 seconds in the first embodiment). Will be. Specifically, when the second drive mode is started, the photosensitive drum 12 is started to rotate so that the linear velocity A is about 415 mm / sec, which is equivalent to that during normal image formation, and the developing roller 13a is The linear velocity B ′ is rotationally driven so as to be reduced to about 265 mm / about, and the linear velocity ratio X (= B ′ / A) becomes about 0.64.
At this time (when the second drive mode is executed), the charging device 14 (charging roller) is applied with a charging bias and the developing roller 13a is applied with a developing bias. The As a result, it is possible to prevent a problem in which toner or carrier adheres to the photosensitive drum 12 from the developer G carried on the developing roller 13a.

As described above, the “second drive mode” is performed after the “first drive mode (developer replenishment mode)” because the developer amount ρ (pumping amount) carried on the developing roller 13a and the development gap PG (development). Depending on the relationship between the roller 13a and the photosensitive drum 12) (in the case where ρ / PG becomes larger than a predetermined value), the photosensitive drum 12 is stopped in rotation. This is because, in the first drive mode in which the developing roller 13a is rotated, as shown in FIG. 6A, a phenomenon that the developer G accumulates at a position upstream of the developing gap occurs. As shown in FIG. 6A, after the developer G accumulates at a position upstream of the developing gap, the photosensitive drum 12 is moved to the normal time in addition to the developing roller 13a that rotates at the same linear velocity as the normal time. If it is rotationally driven at the same linear velocity (when the linear velocity ratio X becomes 1 or more), the developer G accumulated at the upstream position of the development gap is transferred to the development gap as shown in FIG. A problem that the developer is fixed to the developing roller 13a and the photosensitive drum 12 is liable to occur as the pressure is brought into contact. If the developer adheres to the developing roller 13a or the photosensitive drum 12 in such a manner, a streak image is formed on the image or periodic density unevenness occurs.
In contrast, in the first embodiment, even if the developer G accumulates at a position upstream of the development gap as shown in FIG. 6A by executing the first drive mode, the photoconductor Since the developing roller 13a is rotated at a linear velocity B ′ that is slower than the linear velocity A of the drum 12, the developer G accumulated at the upstream position of the developing gap develops as shown in FIG. 6B. The gap gradually enters the gap little by little, and the problem that the developer adheres to the developing roller 13a and the photosensitive drum 12 is less likely to occur.
As described above, when the second drive mode is executed, the normal state in which the normal image forming operation can be performed is returned. In other words, when the second drive mode is executed, the state (agent reservoir) generated by executing the first drive mode returns to the normal state (the state where there is no agent reservoir) equivalent to that at the time of image formation. Become. That is, this “second drive mode” functions as a “agent accumulation removal mode”, and returns to a normal state in which a normal image forming operation is possible as shown in FIG. 6C after the second drive mode. become.

FIG. 8 shows the linear velocity A of the photosensitive drum 12 and the linear velocity B of the developing roller 13a that are driven to rotate after the first drive mode (developer replenishment mode) using the image forming apparatus 1 according to the first embodiment. 3 shows experimental results obtained by visually observing whether or not the developer adheres to the surfaces of the developing roller 13a and the photosensitive drum 12 for each combination when V is varied in various combinations. The experiment was performed under the condition that the agent pool as shown in FIG.
Also from the experimental results shown in FIG. 8, when the agent accumulation as shown in FIG. 6A occurs in the first drive mode, the developing roller is faster than the linear velocity A of the photosensitive drum 12 that is rotationally driven thereafter. By controlling so that the linear velocity B of 13a is reduced (A> B), it was confirmed that the fixing of the developer to the surfaces of the developing roller 13a and the photosensitive drum 12 was prevented.

As described above, in the “second drive mode (agent accumulation removal mode)”, it is important to perform control so that the linear velocity B of the developing roller 13 a is smaller than the linear velocity A of the photosensitive drum 12. When the drive mode is executed, the linear velocity A of the photosensitive drum 12 in the developing gap (opposite position) becomes larger than that at the time of image formation, and the linear velocity B of the developing roller 13a in the developing gap is at the time of image formation. It is also possible to control so that it is equivalent to the above. However, in this case, the first drive motor 61 that can make the rotational speed of the photosensitive drum 12 larger than that at the time of image formation is used, and the first drive motor 61 is increased in size and cost. It will become.
On the other hand, in the first embodiment, as described above, the linear velocity of the photosensitive drum 12 in the developing gap (opposite position) when the second drive mode (agent storage removal mode) is executed. A is controlled to be equal to that at the time of image formation, and the linear velocity B of the developing roller 13a in the development gap is smaller than that at the time of image formation. As a result, the first driving motor 61 and the second driving motor 62 can be prevented from becoming large and expensive, and the developer can be prevented from sticking to the surface of the developing roller 13a and the photosensitive drum 12.

FIG. 9 is a graph showing a change in driving torque of the developing device 13 (second driving motor 62) after starting the second driving mode. The drive torque is converted from the detection result by the current detection unit 63 (a measuring device that detects the value of the current flowing through the second drive motor 62) shown in FIG.
In FIG. 9, a solid line graph is a state in which the developer G is accommodated in the developing device 13 (a state where the first drive mode is normally executed), and a broken line graph is developed in the developing device 13 as a comparison. This is a state in which the agent G is not accommodated (drived in an empty state without replenishing the developer). In time M in FIG. 9, the driving torque increases in both the solid line graph and the broken line graph because a large starting current (starting torque) is generated immediately after the operation of the second drive motor 62 is started. The time N in FIG. 9 is the time until the driving torque decreases and stabilizes in the state where the developer is accommodated, and the time until the driving torque decreases and stabilizes in the state where the developer is not accommodated. The time N is the time required for eliminating the agent pool shown in FIG. 6 (A).
The inventor of the present application measured changes in the driving torque of the developing device 13 shown in FIG. 9 in accordance with the experimental conditions of FIG. 8, and the time N of FIG. It was confirmed that the time N in FIG. 9 was very short and was close to 0 under the experimental conditions where sticking did not occur.

In the first embodiment, when the first drive mode (developer replenishment mode) is not executed during non-image formation, the second drive mode (agent accumulation removal mode) is not executed, and the developing roller 13a. The first drive motor 61 (the first drive motor 61) is set so that the linear speed ratio X when the rotation of the photosensitive drum 12 is started together with the rotation of is equal to that at the time of image formation (approximately 1.5). Driving means) and the second driving motor 62 (second driving means) are controlled.
Specifically, in the first embodiment, the first drive mode is executed only when the developing device 13 is replenished with the developer, and the second drive mode is also executed only at that time. Other startup timings (simply when the main power of the device 1 is turned on, when returning from the standby mode or energy-saving mode, when returning from the jam processing operation, or simply using process control (imaging In the case of (condition adjustment) being executed, etc.), the first driving mode and the second driving mode are not executed, and the photosensitive drum 12 and the developing roller 13a (at the linear speed ratio) are used. The driving of the developing device 13) is started.
Also, as shown in FIG. 4, among the four process cartridges 10Y, 10M, 10C, 10BK (developing device 13), the one to be replenished with the developer G (the black process cartridge 10BK). For other process cartridges 10Y, 10M, and 10C (developing device 13) other than), the first drive mode and the second drive mode are not executed, and the photosensitive drum 12 is operated at a normal linear velocity (linear velocity ratio). And the developing roller 13a (developing device 13) are started to be driven. In other words, the other process cartridges 10Y, 10M, and 10C that are not the targets for replenishing the developer G are those that are the targets for replenishing the developer G (the black process cartridge 10BK). While the first drive mode or the second drive mode is being executed, or thereafter, the photosensitive drum 12 and the developing roller 13a (developing device 13) are started to drive at a normal linear velocity (linear velocity ratio). It will be.
By performing such control, it is possible to prevent a problem that the first drive mode and the second drive mode are executed unnecessarily.

Hereinafter, the control when the developer G is replenished with the developer G described above will be collectively described with reference to the flowchart shown in FIG.
As shown in FIG. 10, first, when the image forming apparatus 1 is started up, it is determined whether or not the developing device 13 is being replenished with the developer G (step S1). Specifically, the presence or absence of a state in which the developer container 70 (and the funnel 71) is connected to the developer replenishing port 13m of the developing device 13 is detected by a detection unit (not shown).
If it is determined that the developer G is being replenished with respect to the developing device 13, the first drive mode (developer replenishment mode) is determined to be that the developer replenishment has been completed. (Steps S2 and S3). Specifically, in the first embodiment, the first drive mode is executed for a preset time D1.
Then, after the first drive mode ends, the second drive mode (agent accumulation removal mode) is executed for a predetermined time D2 (step S4).
Then, after the second drive mode ends, process control (adjustment of image forming conditions) is performed while the developing device 13 and the photosensitive drum 12 are driven at normal speeds (step S5). Here, the process control is a known process performed after the developer is replenished, and the image density of the patch pattern formed on the photosensitive drum 12 or the intermediate transfer belt 17 is optically controlled. The output value of the P sensor to be detected is calibrated, and the values of the charging bias and the developing bias are optimized.
Then, after the process control is completed, a normal printing operation (image forming operation) is performed while the developing device 13 and the photosensitive drum 12 are respectively driven at a normal speed (step S6).
If it is determined in step S1 that the developer G is not replenished with the developer G, steps S2 to S4 are not performed, and steps S5 and subsequent steps are performed. Will be.
This flow is thus completed.

Here, in the first embodiment, the predetermined time D2 in which the second drive mode is executed is increased or decreased according to the increase or decrease in the time D1 in which the first drive mode is executed.
This is because when the time D1 during which the first drive mode is executed becomes longer, the amount of the agent reservoir shown in FIG. 6A also increases than when the time D1 is shorter, so the second drive mode is executed. This is because it is necessary to set the time D2 to be long and to reliably remove the agent pool over time.
Therefore, for example, when the amount of developer to be replenished to the four process cartridges 10Y, 10M, 10C, and 10BK (developing device 13) is different, the process cartridge 10 having a large amount of developer to be replenished is replenished. The time D1 for executing the first drive mode is set to be longer than the process cartridge 10 in which the amount of developer to be reduced is reduced, and the time D2 for executing the second drive mode is set to be longer accordingly. become.

In the first embodiment, the time D2 for executing the second drive mode is set as a constant in advance.
On the other hand, as shown in FIG. 2, the current detection unit 63 (the value of the current flowing through the second drive motor 62) serves as torque detection means for detecting the drive torque applied to the second drive motor 62 (second drive means). In this case, the magnitude of the drive torque is indirectly detected from the change.), And when the drive torque detected by the current detector 63 (torque detector) becomes smaller than a predetermined threshold, It is also possible to control to end the two-drive mode. As described above with reference to FIG. 9, it is possible to determine the state in which the agent reservoir has been removed from the change in the drive torque applied to the second drive motor 62. By performing such control, it is possible to efficiently and reliably remove the agent reservoir generated on the upstream side of the development gap.
Further, it is possible to directly detect the agent pool generated on the upstream side of the development gap using a detection unit such as a photosensor, and to control to end the second drive mode based on the detection result.

As described above, in the first embodiment, at the time of non-image formation, the first driving motor 61 is configured to rotationally drive the developing roller 13a in a state where the rotational driving of the photosensitive drum 12 (image carrier) is stopped. When the “first driving mode” for controlling the (first driving unit) and the second driving motor 62 (second driving unit) is executed, the photosensitive drum 12 is then rotated in addition to the developing roller 13a. The linear velocity ratio X when the rotational driving of the developing roller 13 is started is a ratio B / A of the linear velocity B of the developing roller 13a to the linear velocity A of the photosensitive drum 12 in the developing gap. The “second drive mode” for controlling the first drive motor 61 and the second drive motor 62 is executed for a predetermined time D2.
As a result, even when the rotation driving of the developing roller 13a is performed while the rotation of the photosensitive drum 12 is stopped, the photosensitive drum 12 is rotated in addition to the developing roller 13a after the control. In addition, the developer G collected on the upstream side of the position where the photosensitive drum 12 and the developing roller 13a are opposed to each other is fixed so that the developer G is pressed against the position and is fixed to the developing roller 13a and the photosensitive drum 12. Can be made difficult to occur.

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 11 is a timing chart showing control when the developing device 13 is replenished with the developer and the cleaning blade 15 is new in the image forming apparatus according to the second embodiment. 6 corresponds to FIG. 5 in FIG. FIG. 12 is a timing chart showing control when the developer is not replenished to the developing device 13 and the cleaning blade 15 is new, and corresponds to FIG. 5 in the first embodiment. FIG. 13 is a flowchart showing the overall control in the second embodiment including the control in FIGS. 11 and 12, and corresponds to FIG. 10 in the first embodiment.
The image forming apparatus according to the second embodiment is different from that of the first embodiment in that the “toner supply mode” is executed when the cleaning blade 15 is new.

The image forming apparatus 1 according to the second embodiment is also configured in substantially the same manner as that of the first embodiment, and the “first drive mode (developer replenishment mode)” is the same as that of the first embodiment. After the execution, control is performed so that the “second drive mode (agent accumulation removal mode)” is executed.
Here, in the image forming apparatus 1 according to the second embodiment, the cleaning blade 15 (contacts the photosensitive drum 12 with a predetermined contact pressure and contact angle and is carried on the surface of the photosensitive drum 12. A set detection unit 64 (see FIG. 2) is provided as a new article detecting means for detecting that the untransferred toner is cleaned.
In the first embodiment, the set detection unit 64 (new article detection means) stores various information such as ID chips (usage history and date of manufacture related to the process cartridge 16) installed in the process cartridge 16. ), And determines whether or not the cleaning blade 15 (process cartridge 16) is new from the read information.
Note that the state in which the cleaning blade 15 is new is a state in which the cleaning blade 15 is not used at all as a member for performing the cleaning process, or is used for a short time even if it is used. Define.

  As shown in FIG. 11, in the second embodiment, the “first drive mode (developer replenishment mode)” is executed, and the cleaning blade 15 is set by the set detection unit 64 (new article detection means). Is detected, the developing device 13 develops a predetermined latent image formed on the surface of the photosensitive drum 12 while the “second driving mode (agent accumulation removal mode)” is executed. A “toner supply mode (blade protection mode)” for supplying toner to the cleaning blade 15 is executed.

Specifically, as shown in FIG. 11, when the second drive mode is executed (when the developing device 13 is driven at a low speed and the photosensitive drum 12 is driven at a normal speed), writing is performed. The control unit 2 is controlled to form a predetermined electrostatic latent image on the photosensitive drum 12, and the electrostatic latent image is developed by the developing device 13 and supplied to a predetermined toner image (toner to be supplied to the cleaning blade 15. The toner image is passed through the primary transfer nip portion without being transferred to the intermediate transfer belt 17 at the primary transfer nip portion, and is supplied to the cleaning blade 15 (input). ) Therefore, when the “toner supply mode (blade protection mode)” is executed, the primary transfer bias applied to the primary transfer bias roller 20 is turned off (or a bias having the same polarity as the toner polarity is applied). ing).
In the second embodiment, a toner image (pattern) formed on the photosensitive drum 12 when the “toner supply mode (blade protection mode)” is executed together with the “second drive mode (agent accumulation removal mode)”. ), 15 patterns are formed as one pattern of a solid image of A4 size (320 mm × 210 mm) so that sufficient toner is supplied to the edge portion of the cleaning blade 15 in the width direction.

Such a control is performed because the new cleaning blade 15 is too close to the photosensitive drum 12 and the second driving mode is executed as it is to rotate the photosensitive drum 12. This is because the cleaning blade 15 is drowned or chatter noise is generated.
On the other hand, in the second embodiment, when the cleaning blade 15 is new and the second driving mode is executed and the photosensitive drum 12 is driven to rotate, a toner image (on the photosensitive drum 12 ( The toner image reaches the edge portion of the cleaning blade 15 (the contact portion with the photosensitive drum 12). Therefore, the toner stays at the edge of the cleaning blade 15, and the toner functions as a lubricant interposed between the cleaning blade 15 and the photosensitive drum 12, and the cleaning blade 15 may be drowned. The trouble that the chatter sound is generated is surely reduced. That is, the “toner supply mode” functions as a “blade protection mode” for protecting the cleaning blade 15.

Also, as shown in FIG. 12, in the second embodiment, the “first drive mode (developer replenishment mode)” is not executed, and the cleaning blade 15 is moved by the set detection unit 64 (new article detection means). When a new state is detected, the “second drive mode (agent accumulation removal mode)” is not executed, and the linear speed ratio X2 equivalent to that at the time of image formation (1 in the second embodiment is 1). The toner supply mode (blade protection mode) is executed.
Such control is performed when it is not necessary to set the linear speed ratio X to be low when the second drive mode is not executed, and the linear speed ratio is set equal to that during normal image formation. This is because the developing capability of the developing device 13 (the toner adhesion amount per unit area of the toner image formed on the photosensitive drum 12) is high, and it is easy to form a toner image to be supplied to the cleaning blade 15. is there.
In the second embodiment, the “second drive mode (agent accumulation removal mode)” is not executed, but only the “toner supply mode (blade protection mode)” is executed, and this is formed on the photosensitive drum 12. As a toner image (pattern), six patterns of A4 size (320 mm × 210 mm) solid images are formed as one pattern so that sufficient toner is supplied to the edge portion of the cleaning blade 15 in the width direction.

In the second embodiment, the total area of the toner image (pattern) developed by the developing device 13 when the “toner supply mode” is executed while the “second drive mode” is executed is defined as A1. When the “toner supply mode” is executed without executing the “second drive mode”, the total area of the toner image developed by the developing device 13 is A2, and the linear speed ratio X in the second drive mode is X1 ( In the second embodiment, it is about 0.64.) Assuming that the linear velocity ratio X during image formation is X2,
A1 ≧ A2 × (X2 / X1)
Is controlled so that the following relationship is established.
Specifically, as described above, the number of solid image patterns when the “toner supply mode” is executed while the “second drive mode” is executed is set to 15, and the total area A1 is 320 mm. In contrast to × 210 mm × 15, the number of solid image patterns when the “toner supply mode” is executed without executing the “second drive mode” is set to 15, and the total area A2 is 320 mm. × 210 mm × 6.

Such control is performed because when the second drive mode is executed, the linear speed ratio X of the developing roller 13a with respect to the photosensitive drum 12 is set low, and the linear speed ratio X is equal to that during normal image formation. As compared with the case where the developing device 13 is set, the developing capability in the developing device 13 (the amount of toner adhered per unit area of the toner image formed on the photosensitive drum 12) is reduced, and the amount of toner supplied to the cleaning blade 15 is small. This is because it becomes.
In the second embodiment, a sufficient amount of toner is supplied to a new cleaning blade 15 by increasing the number of patterns so as to compensate for a decrease in the amount of toner adhesion due to a decrease in the linear velocity ratio X in the second drive mode. Therefore, the problem that the cleaning blade 15 is drowned or a chatter noise is reliably reduced.

Hereinafter, the control in the above-described second embodiment will be described together using the flowchart shown in FIG. Note that description of steps common to the flowchart of FIG. 10 described in Embodiment 1 is omitted or simplified as appropriate.
As shown in FIG. 13, first, when the main power supply is turned on and the image forming apparatus 1 is started up, it is determined whether or not the developing device 13 is being replenished with the developer G (see FIG. 13). Step S1).
If it is determined that the developer G is being replenished with respect to the developing device 13, the first drive mode (developer replenishment mode) is determined to be that the developer replenishment has been completed. (Steps S2 and S3).
Then, after the end of the first drive mode, it is determined based on the detection result of the set detection unit 64 whether the cleaning blade 15 is new (step S13). As a result, if it is determined that the cleaning blade 15 is not new, the second drive mode (agent accumulation removal mode) is executed for a predetermined time D2 (step S4), and the flow after step S5 is performed.
On the other hand, if it is determined in step S13 that the cleaning blade 15 is new, the toner supply mode (blade protection mode) is executed for a predetermined time D2 together with the second drive mode (agent accumulation removal mode). (Step S14), the flow after Step S5 is performed.

On the other hand, when it is determined in step S1 that the developer G has not been replenished with the developer G, the set detection unit 64 detects whether the cleaning blade 15 is new. A determination is made based on the result (step S11). As a result, when it is determined that the cleaning blade 15 is not new, the flow after step S5 is performed.
On the other hand, if it is determined in step S11 that the cleaning blade 15 is new, the second drive mode (agent reservoir removal mode) is not performed, and the linear speed ratio during normal image formation is not performed. At X, the toner supply mode (blade protection mode) is executed for a predetermined time (step S12), and the flow after step S5 is performed.

In the second embodiment, when the toner supply mode is executed, the primary transfer bias is not applied to the primary transfer bias roller 20 so that the toner image (pattern) formed in the development process is not applied. ) Is supplied to the cleaning blade 15 without being primarily transferred to the intermediate transfer belt 17.
In contrast, the intermediate transfer belt 17 (primary transfer bias roller 20) can be separated from the photosensitive drum 12 by a known contact / separation mechanism, and when the toner supply mode is executed, the intermediate transfer belt 17 (primary transfer bias roller 20) can be separated. The transfer belt 17 (primary transfer bias roller 20) is separated from the photosensitive drum 12, and the toner image (pattern) formed in the development process is not transferred to the intermediate transfer belt 17 and transferred to the cleaning blade 15. It can also be supplied.

As described above, in the second embodiment, similarly to the first embodiment, during the non-image formation, the developing roller 13a is stopped in a state where the rotational driving of the photosensitive drum 12 (image carrier) is stopped. When the “first drive mode” for controlling the first drive motor 61 (first drive means) and the second drive motor 62 (second drive means) is executed so as to rotate the drive roller, the developing roller is thereafter In addition to the rotational driving of 13a, the linear speed ratio X (the ratio B / A of the linear speed B of the developing roller 13a to the linear speed A of the photosensitive drum 12 in the development gap) when the rotational driving of the photosensitive drum 12 is started. “Second drive mode” for controlling the first drive motor 61 and the second drive motor 62 so that the ratio is smaller than 1 is executed for a predetermined time D2.
As a result, even when the rotation driving of the developing roller 13a is performed while the rotation of the photosensitive drum 12 is stopped, the photosensitive drum 12 is rotated in addition to the developing roller 13a after the control. In addition, the developer G collected on the upstream side of the position where the photosensitive drum 12 and the developing roller 13a are opposed to each other is fixed so that the developer G is pressed against the position and is fixed to the developing roller 13a and the photosensitive drum 12. Can be made difficult to occur.

In each of the embodiments described above, the present invention is applied to the image forming apparatus 1 in which the developing device 13 is unitized as a constituent member of the process cartridge 10 together with other image forming members. However, the application of the present invention is not limited to this, and an image forming member such as the developing device 13 is not formed as a process cartridge but is configured to be detachably installed on the image forming apparatus as a single unit. Of course, the present invention can be applied even if it is.
In the present application, “process cartridge” means a charging device (charging unit) for charging an image carrier, a developing device (developing unit) for developing a latent image formed on the image carrier, and an image carrier. It is defined as a unit in which at least one of the cleaning units for cleaning the top and the image carrier are integrated and installed detachably with respect to the image forming apparatus main body.

In each of the above-described embodiments, one developing roller 13a is installed, two conveying screws as conveying members are installed in the vertical direction, and the doctor blade 13c is installed above the developing roller 13a. The present invention was applied to 13. However, the application of the present invention is not limited to this, and the present invention can be applied to various types of developing devices. For example, a developing device in which two or more developing rollers are arranged in parallel in the vertical direction so that the developing roller faces the image carrier, a developing device in which two conveying screws are arranged in parallel in the horizontal direction, or three or more conveying devices Of course, the present invention is also applied to a developing device in which a screw is installed, a developing device in which a paddle-shaped roller is used as a conveying member, a developing device in which a doctor blade is installed below the developing roller, and the like. be able to.
Even in such a case, the same effects as those of the above-described embodiments can be obtained.

In each of the above-described embodiments, the developer container 70 is set from the outside with the main body door 100 opened while the developing device 13 is set in the image forming apparatus 1, and the developer is supplied to the developing device 13. The present invention is applied to an image forming apparatus that performs replenishment. On the other hand, as in Patent Document 1, development is performed from a developer container (developer preset case) installed above the developing device with the main body door closed with the developing device set in the image forming apparatus. Naturally, the present invention can also be applied to an image forming apparatus that replenishes developer to the apparatus.
Even in such a case, it is possible to obtain substantially the same effects as those of the above embodiments.

In each of the above embodiments, the present invention is applied to an image forming apparatus in which the process linear velocity (the linear velocity A of the photosensitive drum 12 or the conveyance velocity of the recording medium P) is fixed to a predetermined value. Applied. On the other hand, the present invention can also be applied to an image forming apparatus in which the process linear velocity is varied in multiple stages by a thick paper mode (low speed mode) or the like. Even in that case, by setting the first and second drive modes in accordance with the respective process linear velocities, it is possible to obtain the same effects as those of the above-described embodiments.
In each of the above embodiments, the present invention is applied to an image forming apparatus in which the first drive mode is executed when the developer is replenished. However, the application of the present invention is not limited to this, and image formation in which control (first drive mode) for rotationally driving the developing roller 13a in a state in which the rotational driving of the photosensitive drum 12 is stopped is performed at a predetermined timing. If the apparatus is an apparatus (for example, an image forming apparatus that executes the first drive mode when a new developing device is set in the main body of the image forming apparatus), the present invention can be applied to all of them. it can. Even in such a case, it is possible to obtain substantially the same effects as those of the above embodiments.

In each of the above embodiments, the present invention is applied to an image forming apparatus that uses a two-component developer composed of toner and a carrier as a developer accommodated in the developing device 13. On the other hand, the present invention is also applied to an image forming apparatus using a one-component developer (including the case where an additive or the like is added) composed only of toner as a developer accommodated in the developing device. Can be applied. In the case of using such a one-component developing type developing device, in addition to the type in which the developing roller faces the image carrier with a gap, the type in which the developing roller contacts the image carrier. However, the present invention can be applied.
In each of the above embodiments, the present invention is applied to an image forming apparatus in which the developing roller 13a and the photosensitive drum 12 rotate in the rotating direction at a position where the developing roller 13a and the photosensitive drum 12 face each other. did. On the other hand, the present invention can also be applied to an image forming apparatus in which the developing roller and the photosensitive drum rotate in the counter direction at a position where the developing roller and the photosensitive drum face each other.
Even in such a case, substantially the same effects as those of the above embodiments can be obtained.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1 image forming apparatus (image forming apparatus main body),
10, 10Y, 10M, 10C, 10BK process cartridge,
12 Photosensitive drum (image carrier),
13 Development device,
13a Development roller (developer carrier),
13c Doctor blade (developer regulating member),
14 charging device,
15 Cleaning blade,
61 1st drive motor (1st drive means),
62 second drive motor (second drive means),
63 Current detector (torque detector),
64 set detection unit (new article detection means),
G Developer.

Japanese Patent No. 4695296 JP 2010-96923 A

Claims (14)

An image carrier that is rotationally driven in a predetermined direction by the first driving means;
The developer is housed inside, and is driven to rotate in a predetermined direction by the second driving means so that a linear velocity ratio with respect to the linear velocity of the image carrier at a position facing the image carrier is a predetermined value of 1 or more. A developing device comprising a developing roller for developing a latent image formed on the surface of the image carrier,
With
During non-image formation, a first drive mode is executed to control the first drive means and the second drive means so as to rotationally drive the developing roller in a state where the rotational drive of the image carrier is stopped. In this case, the first drive means and the second drive means are set so that the linear velocity ratio is less than 1 when the rotation of the image carrier is started in addition to the rotation of the developing roller. An image forming apparatus characterized in that the second drive mode for controlling is executed for a predetermined time. A charging device that charges the surface of the image carrier when a charging bias is applied;
When the first drive mode is executed, control is performed so that the charging bias is not applied to the charging device and the developing bias is not applied to the developing roller,
2. The control according to claim 1, wherein when the second drive mode is executed, the charging bias is applied to the charging device and the developing bias is applied to the developing roller. Image forming apparatus.   When the second drive mode is executed, the linear velocity of the image carrier at the facing position is equal to that at the time of image formation, and the linear velocity of the developing roller at the facing position is the same as that at the time of image formation. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled to be smaller than the image forming apparatus.   The said predetermined time when said 2nd drive mode is performed is increased / decreased according to increase / decrease in the time when said 1st drive mode is performed, The Claim 1 characterized by the above-mentioned. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the image forming apparatus returns to a normal state in which a normal image forming operation can be performed by executing the second drive mode. A torque detecting means for detecting a driving torque applied to the second driving means;
6. The second drive mode is controlled so as to end when the drive torque detected by the torque detection means becomes smaller than a predetermined threshold value. The image forming apparatus described in 1.   When the first drive mode is not executed during non-image formation, the second drive mode is not executed, and the line when the rotation of the image carrier is started together with the rotation of the developing roller is started. The image forming apparatus according to claim 1, wherein the first driving unit and the second driving unit are controlled so that a speed ratio is equal to that at the time of image formation. .   In the first driving mode, the developing device and the image carrier are mounted on the image forming apparatus, and the developer contained therein is empty or close to the inside. The image forming apparatus according to claim 1, wherein the image forming apparatus is executed when a developer is filled in the image forming apparatus. A cleaning blade that contacts the image carrier and cleans untransferred toner carried on the surface of the image carrier;
New article detecting means for detecting that the cleaning blade is new,
With
When the first drive mode is executed and the state where the cleaning blade is new is detected by the new article detection means, the surface of the image carrier is executed while the second drive mode is executed. 9. The image formation according to claim 1, wherein a toner supply mode in which a predetermined latent image formed on the surface of the toner is developed by the developing device and toner is supplied to the cleaning blade is executed. apparatus.   When the first drive mode is not executed, and when the state where the cleaning blade is new is detected by the new article detection means, the second drive mode is not executed and the one at the time of image formation. The image forming apparatus according to claim 9, wherein the toner supply mode is executed at the same linear velocity ratio. The total area of the toner image developed by the developing device when the toner supply mode is executed while the second drive mode is executed is defined as A1, and the toner supply mode is set without executing the second drive mode. When the total area of the toner image developed by the developing device when executed is A2, the linear speed ratio in the second drive mode is X1, and the linear speed ratio during image formation is X2. ,
A1 ≧ A2 × (X2 / X1)
The image forming apparatus according to claim 10, wherein control is performed so that the following relationship is established. The developing device includes a developer regulating member that regulates the amount of developer carried on the surface of the developing roller above the developing roller,
Both the image carrier and the developing roller are rotationally driven so as to move downward from above at the facing position,
The image forming apparatus according to claim 1, wherein the developer is a two-component developer including a toner and a carrier. A process cartridge that is detachably attached to an image forming apparatus,
An image carrier that is rotationally driven in a predetermined direction;
The image carrier is housed in a developer and is rotationally driven in a predetermined direction so that a linear velocity ratio with respect to a linear velocity of the image carrier at a position facing the image carrier is a predetermined value of 1 or more. A developing device including a developing roller for developing a latent image formed on the surface of the body;
With
In the non-image formation, when the first drive mode for controlling the developing roller to rotate is performed with the rotation of the image carrier stopped, in addition to the rotation driving of the developing roller, And a second drive mode for controlling the linear speed ratio so as to be smaller than 1 when rotation of the image carrier is started for a predetermined time. A cleaning blade for cleaning the untransferred toner carried on the surface of the image carrier in contact with the image carrier;
When the first drive mode is executed, and when a state where the cleaning blade is new is detected by the new article detection means, the second drive mode is executed and the surface of the image carrier is detected. The process cartridge according to claim 13, wherein a toner supply mode in which a predetermined latent image formed is developed by the developing device and toner is supplied to the cleaning blade is executed.

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