JP6525200B2 - Image forming apparatus and process cartridge - Google Patents

Description

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

  Conventionally, in an image forming apparatus such as a copying machine or a printer, a two-component developer (additive agent) consisting of toner and carrier while driving a developing device in an empty state (or a state close thereto) during non-image formation There is also known a technology for uniformly replenishing a developer such as, for example, the case of adding etc.) to the inside of a developing device (for example, see Patent Documents 1 and 2).

More specifically, in Patent Document 1, when a developer preset case containing a new developer is installed on the top of a new developing device, and the developing device starts to be used, the developing device or the photosensitive drum (image A technology is disclosed in which the developer is uniformly replenished from the developer preset case into the developing device while driving the carrier.
Further, according to Patent Document 2, with respect to a new developing device mounted on the image forming apparatus and a developing device at the time of developer replacement with the main body cover (developer replenishment cover) of the image forming apparatus opened, Connect a developer container containing a new developer from the outside, and while replenishing the developer from inside the developer container to the inside of the developing device while driving the developing device and photosensitive drum (image carrier) Technology is disclosed.

The conventional image forming apparatus replenishes the developer to the inside of the developing device while driving the developing device in an empty state (or in a state close to it), so that the operator manually drives the developing device. As compared with the case of replenishing the developer, the effect of uniformly replenishing the developer into the developing device in a relatively easy and short time can be expected.
However, in the prior art, in addition to the developing roller (developing device) at the time of replenishment of the developer, the photosensitive drum (image carrier) is also rotationally driven, so that the cleaning blade in sliding contact with the photosensitive drum There is a possibility that the photosensitive drum, the cleaning blade, and the like may be worn out prematurely.

On the other hand, it may be considered that control is made to stop the rotational driving of the photosensitive drum at the time of replenishment of the developer and drive only the developing roller (developing device). However, in that case, when the developer is accumulated on the upstream side of the facing position (developing gap) between the photosensitive drum and the developing roller, and then the photosensitive drum is rotationally driven in addition to the developing roller, The developer accumulated on the upstream side of the facing position of the drum and the developing roller is liked as one piece so as to be in pressure contact with the facing position, and there is a possibility that the developer adheres to the developing roller or the photosensitive drum. There is. Then, when the developer adheres to the developing roller and the photosensitive drum as such, a streak image is formed on the image and periodic density unevenness occurs.
In addition, such a problem is not limited to the time of replenishment of the developer, and can be commonly caused when control is performed to rotationally drive the developing roller in a state in which the rotational drive of the photosensitive drum is stopped. is there.

  The present invention has been made to solve the above-described problems, and even when control is made to rotationally drive the developing roller in a state in which rotational driving of the image carrier is stopped, development is carried out after the control. When the image bearing member is rotationally driven in addition to the roller, the developer accumulated on the upstream side of the facing position of the image bearing member and the developing roller is favored so that it is pressed against the facing position. An object of the present invention is to provide an image forming apparatus and a process cartridge which are less likely to cause a problem of being stuck to the body.

  In the image forming apparatus according to the first aspect of the present invention, an image carrier rotatably driven in a predetermined direction by the first drive unit, a developer is contained therein, and the image carrier is opposed to the image carrier. The latent image formed on the surface of the image carrier is developed by being rotationally driven in a predetermined direction by the second driving means such that the linear velocity ratio to the linear velocity of the image carrier at the position becomes a predetermined value of 1 or more. And a developing device provided with a developing roller, wherein the first driving means and the second driving means are configured to rotationally drive the developing roller in a state in which the rotational driving of the image carrier is stopped at the time of non-image formation. Such that the linear velocity ratio when the rotational drive of the image carrier is started in addition to the rotational drive of the developing roller after that when the first drive mode for controlling 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 control is made to rotationally drive the developing roller in a state in which rotational driving of the image carrier is stopped, when the image carrier is rotationally driven in addition to the developing roller after the control. The image forming member is less likely to have a problem that the developer accumulated on the upstream side of the facing position of the image bearing member and the developing roller is liked as one in pressure contact with the facing position and fixed on the developing roller and the image bearing member An apparatus and process cartridge can be provided.

FIG. 1 is an overall configuration diagram showing an image forming apparatus in Embodiment 1 of the present invention. It is a block diagram which shows an image formation part. (A) A schematic sectional view of the upper portion of the developing device in the longitudinal direction, and (B) a schematic sectional view of the lower portion of the developing device in the longitudinal direction. FIG. 10 is a schematic perspective view showing a state in which the developing device in the process cartridge for black is replenished with a developer. 5 is a timing chart showing control when replenishing the developing device with a developer. FIG. 5A is a schematic view in the first drive mode, FIG. 4B is a schematic view in the second drive mode, and FIG. 4C is a schematic view in the normal image formation. FIG. 7 is a schematic view 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. 7 is a table showing the presence or absence of the developer fixed on 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 image development apparatus after starting a 2nd drive mode. 6 is a flowchart showing control when replenishing the developing device with the developer. 14 is a timing chart showing control when the developing device is replenished with a developer and the cleaning blade is new in the image forming apparatus in Embodiment 2 of the present invention. 7 is a timing chart showing control when the developing device is not replenished with the developer and the cleaning blade is new. 7 is a flowchart showing control in Embodiment 2;

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the redundant description will be appropriately simplified or omitted.

Embodiment 1
The 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 type color copying machine as an image forming apparatus, 2 is a writing unit for emitting laser light based on input image information, 3 is a document conveying unit for conveying a document D to a document reading unit 4, and 4 is A document reading unit for reading image information of a document D, a paper feeding unit 7 in which a recording medium P such as a transfer sheet is stored, a registration roller (timing roller) 9 for adjusting the conveyance timing of the recording medium P, 10Y, 10M, 10C and 10BK indicate process cartridges (image forming units) on which toner images of respective colors (yellow, magenta, cyan and black) are formed.

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

Hereinafter, an operation at the time of normal color image formation in the image forming apparatus will be described.
The image forming process performed on the photosensitive drum 12 of each of the process cartridges 10Y, 10M, 10C, and 10BK can also be referred to FIG.

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

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

On the other hand, the photosensitive drums 12 of the four process cartridges 10Y, 10M, 10C, and 10BK respectively rotate in the counterclockwise direction in FIG. Then, first, the surface of the photosensitive drum 12 is uniformly charged at a portion facing the charging device 14 (charging roller) (charging step). Thus, a charging 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 in correspondence with each color. Each laser beam passes through a separate optical path for each of yellow, magenta, cyan and black color components (exposure step).

  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 laser beam of the yellow component is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 12 by the polygon mirror rotating 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 in the drawing, and an electrostatic latent image corresponding to the magenta component is formed. The laser beam of the cyan component is irradiated onto the surface of the photosensitive drum 12 of the third process cartridge 10C from the left in the drawing, and an electrostatic latent image of the cyan component is formed. The laser beam of the black component is irradiated to the surface of the photosensitive drum 12K of the fourth process cartridge 10BK from the left in the drawing, and an electrostatic latent image of the black component is formed.

After that, the surface of the photosensitive drum 12 on which the electrostatic latent image of each color is formed reaches the position facing the developing device 13 (developing unit). Then, the toners of the respective colors are supplied from the respective developing devices 13 onto the photosensitive drum 12, and the latent image on the photosensitive drum 12 is developed (developing step).
Thereafter, the surfaces of the photosensitive drums 12 after the developing step reach the opposing portion (primary transfer nip portion) with the intermediate transfer belt 17 respectively. Here, the primary transfer bias roller 20 is disposed at each of the opposing portions 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 of a polarity different from the toner polarity is applied), the exposure of each of the process cartridges 10Y, 10M, 10C, 10BK on the intermediate transfer belt 17 is performed. The toner images of the respective colors formed on the body drum 12 are sequentially superimposed and transferred (this is a primary transfer step).

Then, the surfaces of the photosensitive drums 12 after the transfer process reach the 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 (a cleaning step).
Thereafter, the surface of the photosensitive drum 12 passes a charge removing unit (not shown), and a series of image forming processes on the photosensitive drum 12 end.

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 superimposed and transferred (carried) travels in the clockwise direction in FIG. The position opposite to the transfer bias roller 18 is reached. 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 (second transfer process).
Thereafter, the surface of the intermediate transfer belt 17 reaches the position of the intermediate transfer belt cleaning unit 19. Then, the non-transferred toner adhering to the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit 19, and a series of transfer processes on the intermediate transfer belt 17 are completed.

Here, the recording medium P conveyed between the intermediate transfer belt 17 and the secondary transfer bias roller 18 (in the secondary transfer nip) is conveyed from the paper feeding unit 7 via the registration roller 9 and the like. It is
Specifically, the recording medium P fed by the paper feeding roller 8 from the paper feeding unit 7 storing 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 time.

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 process is discharged as an output image from the apparatus main body 1 by the paper discharge roller, and a series of image forming processes are 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, a lubricant supplying unit 16 (lubricating agent supply for supplying a lubricant onto the photosensitive drum 12) And so on. The process cartridge 10 is configured to be removable (replaceable) with respect to the apparatus main body 1.
Since the process cartridges of the respective colors have substantially the same structure, the process cartridge, the photosensitive drum and the developing device in FIGS. 2 and 3 etc. are different from the alphabet (Y, C, M, BK) of the reference numerals. Shown.

Here, the photosensitive drum 12 as an image carrier is a negatively chargeable 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 a conductive support as a base layer, an undercoat layer as an insulating layer, a charge generation layer as a photosensitive layer, a charge transport layer, and a protective layer (surface layer) in this order. It is 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 unit. In the first embodiment, the charging device 14 (charging roller), the lubricant supply roller 16a, and the conveying screw 15b, which will be described later, are also transmitted to the first driving motor 61 via the gear train as shown in FIG. It is rotationally driven in the direction of the arrow shown.

The charging device 14 is a charging roller (roller member) formed by covering an elastic layer having a medium resistance on the outer periphery of a conductive core (shaft), and rotates the photosensitive drum 12 with respect to the lubricant supply device 16. It is disposed to abut on the photosensitive drum 12 at the downstream side in the direction.
Then, 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 photosensitive drum 12 opposed thereto.
Although the charging device 14 is in contact with the photosensitive drum 12 in the first embodiment, the charging device 14 may be opposed to the photosensitive drum 12 with a minute gap without contacting the photosensitive drum 12.

The cleaning blade 15 (cleaning unit) is disposed downstream of the lubricant supply device 16 in the rotational direction of the photosensitive drum 12. 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 at a predetermined pressure. As a result, deposits such as untransferred toner deposited on the photosensitive drum 12 are mechanically scraped off and collected in the process cartridge 10. Then, the toner collected in the process cartridge 10 is disposed as a waste toner in a waste toner collecting container (not shown, and is detachably installed at the back side of the main body 1 of FIG. It is conveyed by the conveyance screw 15b. Here, as the adhering matter adhering to the photosensitive drum 12, paper dust generated from the recording medium P (paper) and discharge products generated on the photosensitive drum 12 at the time of discharge by the charging device 14 in addition to untransferred toner , Additives added to the toner, and the like.
The cleaning blade 15 in the first embodiment also functions as a thinning blade for thinning 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-like roller) in sliding contact with the photosensitive drum 12 and the solid lubricant 16b, and the solid lubricant 16b. It comprises a member 16e, a solid lubricant 16b, and a compression spring 16c that biases the holding member 16e toward the lubricant supply roller 16a.
The lubricant is supplied onto the photosensitive drum 12 by the lubricant supply device 16 configured as described above. The lubricant supplied onto the photosensitive drum 12 is thinned by the cleaning blade 15 disposed downstream of the lubricant supply device 16.

  Referring to FIGS. 2 and 3, in the developing device 13, the developing roller 13 a as a developer bearing member faces the photosensitive drum 12 with a minute gap (about 0.2 to 0.25 mm). The developing region (developing nip portion) where the photosensitive drum 12 and the magnetic brush are in contact is formed at both opposing positions (developing gap). In the developing device 13, a developer G (two-component developer) composed of toner T and carrier C is accommodated. Then, 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, 50BK (toner containers) accommodate toner T for being 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 (refer to FIG. 3) installed in the developing device 13, not shown. The toner T is appropriately replenished from the toner replenishing port 13e toward the developing device 13 from the corresponding toner cartridge among the four toner cartridges 50Y, 50M, 50C, and 50BK via the toner replenishing device described above.
Note that the replenishment of the toner T is not limited to the information of the toner density, and is performed based on the information of the image density detected from the reflectance of the toner image formed on the photosensitive drum 12 and the intermediate transfer belt 17 or the like. May be Also, these different pieces of information may be combined to determine the implementation of the toner T replenishment.
Also, as a toner replenishing device for replenishing the developing device 13 with toner, there are known devices such as one that conveys and replenishes toner using a conveyance auger, one that conveys and replenishes toner together with air using a screw pump, etc. The thing can be used.
The four toner cartridges 50Y, 50M, 50C, and 50BK are configured to be attachable to and detachable from the apparatus main body 1 of FIG. 1 from the front side (in the operation direction front side) 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, conveyance screws 13b1 and 13b2 (auger screws) as conveyance members, a doctor blade 13c as a developer restriction 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 has a sleeve 13a2 formed of a cylindrical nonmagnetic material such as aluminum, stainless steel, brass, conductive resin, etc., and a second drive motor 62 (gear installed on the sleeve shaft as a second drive means). Drive gear is provided to be rotated by the. In the sleeve 13a2 of the developing roller 13a, magnets 13a1 for forming a plurality of magnetic poles are fixed non-rotatably on the circumferential surface of the sleeve 13a2 (the magnet shaft is lightly press-fitted to 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 at this position to an appropriate amount (the amount of pumping up per unit area is about 30 to 38 mg / cm ² ), the facing position with the photosensitive drum 12 ( To the developing region). Then, the photosensitive drum is formed by the electric field formed in the developing area (the developing electric field which is the 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 attracted to the latent image formed on the surface 12.

  The doctor blade 13c as a developer regulating member is a substantially plate-like member formed of a nonmagnetic material, and is disposed 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.

Then, 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 downward from above at the opposing position (developing gap).
Here, in the first embodiment, the developing roller 13a has the same linear velocity A (the linear velocity of the outer peripheral surface of the photosensitive drum 12 at the position facing the photosensitive drum 12 (image carrier), and is 415 mm. The developing process is performed by being rotationally driven in a predetermined direction by the second drive motor 62 (second drive means) such that the linear velocity ratio X with respect to 1 / 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 step (during image formation) (the linear velocity at the position facing the photosensitive drum 12, and is equivalent to 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, by causing the developing roller 13a to travel relatively faster than the photosensitive drum 12 in the developing region, it is possible to perform the developing process in which the image quality is improved.

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

The two conveying screws 13b1 and 13b2 (conveying members) longitudinally move the developer G contained in the developing device 13 (in the direction perpendicular to the sheet of FIG. 2 and in the left-right direction of FIG. 3, the developing roller 13a). In the same direction as the rotation axis direction of
The first conveyance screw 13b1 as a first conveyance member is disposed at a position facing the developing roller 13a, and conveys the developer G horizontally in the longitudinal direction (rotational axis direction) (see FIG. 3A). The developer G is supplied onto the developing roller 13a at the position of the scooping magnetic pole (the supply in the direction of the white arrow in FIG. 3A).

The second conveyance screw 13b2 as a second conveyance member is disposed at a position below the first conveyance screw 13b1 and at a position facing the developing roller 13a. Then, the developer G separated from the developing roller 13a (the developer G separated from the developing roller 13a by the developer separating magnetic pole after the developing process, and is separated in the direction of the white arrow in FIG. 3B). Is conveyed horizontally in the longitudinal direction (the conveyance in the right direction indicated by the broken arrow in FIG. 3B).
Then, the second conveyance screw 13b2 is configured such that the developer G circulated from the downstream side of the conveyance path by the first conveyance screw 13b1 via the first relay portion 13g is disposed upstream of the conveyance path by the first conveyance screw 13b1. It conveys via the relay part 13f (It is the conveyance shown to the dashed-dotted line arrow of FIG. 3.).
Similar to the developing roller 13a and the photosensitive drum 12, the two conveying screws 13b1 and 13b2 are disposed so that the rotation axis is substantially horizontal. In each of the two conveying screws 13b1 and 13b2, the screw portion is spirally wound around the rotation shaft portion.

In addition, the conveyance path (1st conveyance path) by 1st conveyance screw 13b1 and the conveyance path (2nd conveyance path) by 2nd conveyance screw 13b2 are separated by the wall part.
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 portion. It communicates through 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 swells, and the first conveyance screw 13b1 causes the first conveyance screw 13b1 to It is transported (supplied) to the upstream side of the transport path.
Further, the downstream side of the transport path by the first transport screw 13b1 and the upstream side of the transport path by the second transport screw 13b2 are in communication via the first relay portion 13g. Then, the developer G not 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 order to improve the transportability of the developer in the second relay portion 13f (the 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 winding direction of the screw is formed in the opposite direction may 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 conveyance screws 13b1 and 13b2. That is, when the developing device 13 is operated, the developer G contained in the device flows in the direction of the dashed arrow in FIG. Then, as described above, the supply path of the developer G to the developing roller 13a (which is the first conveying path by the first conveying screw 13b1) and the recovery path of the developer G separated from the developing roller 13a (second conveying screw 13b2), the density deviation of the toner image formed on the photosensitive drum 12 can be reduced.

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

  Here, referring to FIG. 3 and FIG. 4, the developing device 13 (process cartridge 10) in the first embodiment is an upper side of the second conveyance path by the second conveyance screw 13b 2 on the upstream side, The developer replenishing port 13m for replenishing the developer G to the inside of the developing device 13 is 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 except when the operation of replenishing the two-component developer G to the developing device 13 is performed.

Then, when the developer G is filled into the developing device 13 in an empty state (or a state near it) in which the developer G is not stored, as shown in FIG. With the image forming apparatus 1 mounted on the image forming apparatus 1, the main body door 100 (main body cover) is opened in the direction of the arrow around the hinge to expose the process cartridges 10 Y, 10 M, 10 C, 10 BK. A funnel 71 (relay member) is externally connected to the replenishment port 13m, and a developer container 70 (new developer G is accommodated) 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 (charged) into the developing device 13 from the developer container 70 via the funnel 71. Thus, by replenishing the developer G from the developer replenishment port 13m while driving the developing device 13, the developer G fed from the developer replenishment port 13m is circulated and conveyed by the two conveyance screws 13b1 and 13b2. As compared with the case where the operator manually drives the developing device 13 and replenishes the developer G, the developer G is uniformly replenished in the developing device 13 in a simple and short time. be able to.
In FIG. 4, the state in which the developer G is replenished to the process cartridge 10BK for black (the developing device 13) among the four process cartridges 10Y, 10M, 10C, and 10BK (developing device 13) is illustrated. However, the developer G can be similarly replenished to the other process cartridges 10Y, 10M and 10C (developing device 13).

As described above, when replenishing the developer G to the empty developing device 13, the case where a new developing device 13 (process cartridge) is installed in the image forming apparatus 1 or the life of the existing developing device 13 is reached. In some cases, the developer G (carrier C) is discarded and replaced with a new developer G (during developer replacement). In particular, at the time of the latter developer replacement, it is necessary to carry out an operation for removing the existing developer G which has reached the end of the life from the existing developing device 13. Such an operation is performed by the existing developing device 13 (process The cartridge 10) can be taken out of the image forming apparatus 1 and manually operated, or, if the developing device 13 is provided with an openable / closable developer outlet (connected to a waste agent container), the developer It can also be performed automatically while driving the developing device in the state where the discharge port is opened.
In any case, such a replenishment operation of the developer G is a special operation performed in a state in which the main body door 100 is opened unlike a normal image forming operation, and therefore an operator such as a serviceman can form an image. Special key input is performed using the operation panel (not shown) of the apparatus 1 and executed.

Here, 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 operated). However, the driving of the photosensitive drum 12 is stopped (the driving of the first driving motor 61 is stopped). That is, at the time of replenishment of the developer G, 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 rotationally driven). .
As a result, at the time of replenishment of the developer G, the cleaning blade 15 comes into sliding contact with the photosensitive drum 12 to cause blurring or abnormal noise, or the photosensitive drum 12, the cleaning blade 15, the charging device 14, etc. It is possible to reduce problems such as premature wear of the
Particularly, 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. Also, the application of high voltage such as charging bias applied to the charging device 14 is prevented so that a problem that the operator touches the member to which the high voltage is applied does not occur. When the photosensitive drum 12 is rotationally driven with the developing bias and the charging bias turned off as described above, the toner in the developer G carried on the developing roller 13 a becomes a dirt toner on the surface of the photosensitive drum 12. The toner concentration of the developer G in the developing device 13 may be reduced, or the background dirt toner on the photosensitive drum 12 may be scattered to stain the inside of the machine with the toner. From this point of view as well, stopping the driving of the photosensitive drum 12 at the time of replenishment of the developer G has a significant meaning.

Hereinafter, characteristic control executed in the image forming apparatus 1 (the process cartridge 10) in the first embodiment will be described in detail with reference to FIGS.
Referring to FIG. 5, the image forming apparatus 1 according to the first embodiment is configured such that the photosensitive drum 12 is not formed (at the timing when the normal image forming process is not performed on the photosensitive drum 12). The first drive motor 61 (first drive means) and the second drive motor 62 (second drive means) are controlled to rotationally drive the developing roller 13a in a state where the rotational drive of the (image carrier) is stopped. When the first drive mode is executed, the linear velocity 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 “second drive mode” for controlling the first drive motor 61 and the second drive motor 62 is set such that the ratio B / A of the linear velocity B of the developing roller 13a to the velocity A is smaller than 1. time Only 2 are executed. Then, after the second drive mode is executed, the linear velocity ratio X is returned to the normal value (1.5 in the first embodiment), and process control (adjustment of image forming conditions) is performed. The normal image forming operation (printing operation) is performed.

Specifically, in the first embodiment, the “first drive mode” is 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. In the mounted state, the developer replenishment mode is executed when the developer G is filled into the developing device 13 in which the developer accommodated in the interior is empty or close thereto. In the "first drive mode (developer replenishment mode)", as shown in FIG. 6A, the developing roller 13a (developing device 13) (the developing device 13) is stopped by the second drive motor 62 while the rotation of the photosensitive drum 12 is stopped. Is driven to rotate at a normal speed (a linear speed or rotation speed at which 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 not to be applied (other biases such as transfer bias are also turned off).
The time D1 during which this "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 transport screws 13b1 and 13b2 in the developing device 13, etc. In addition, it is set in advance to a fixed value (about 30 seconds in the first embodiment).

In the first embodiment, when such a "first drive mode (developer replenishment mode)" is executed, the linear velocity A of the photosensitive drum 12 is always immediately after that in the developing roller 13a. The "second drive mode" for operating the first drive motor 61 and the second drive motor 62 in a state in which the linear velocity B 'is reduced is executed for a predetermined time D2 (about 10 seconds in the first embodiment). It will be Specifically, when the second drive mode is started, rotational driving of the photosensitive drum 12 is started so that the linear velocity A becomes 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 decelerated to about 265 mm /, and their linear velocity ratio X (= B' / A) becomes about 0.64.
At this time (when the second drive mode is executed), the charging bias is applied to the charging device 14 (charging roller), and the developing bias is controlled to be applied to the developing roller 13a. Ru. As a result, it is possible to prevent the problem that toner or carrier adheres on the photosensitive drum 12 from the developer G carried on the developing roller 13a.

As described above, the reason why the “second drive mode” is performed after the “first drive mode (developer replenishment mode)” is the developer amount ρ (the amount by which the developer is squeezed) carried on the developing roller 13a, the development gap PG (development Depending on the relationship between the opposing distance 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 rotating. This is because, in the first drive mode in which the developing roller 13a is rotated, as shown in FIG. 6A, a phenomenon in which the developer G is accumulated at a position on the upstream side of the developing gap occurs. As shown in FIG. 6A, after the developer G is accumulated at a position on the upstream side of the development gap, in addition to the developing roller 13a rotating at the same linear velocity as normal, the photosensitive drum 12 is When rotation drive is performed at the same linear velocity (when the linear velocity ratio X becomes 1 or more), the developer G accumulated at the position on the upstream side of the development gap is, as shown in FIG. As a result, the developer tends to stick to the developing roller 13 a and the photosensitive drum 12. Then, when the developer adheres to the developing roller 13a and the photosensitive drum 12 as such, a streak image is formed on the image or periodic density unevenness occurs.
On the other hand, in the first embodiment, even when the developer G is accumulated at the position on the upstream side of the development gap as shown in FIG. Since the developing roller 13a is rotated at a linear velocity B 'slower than the linear velocity A of the drum 12, as shown in FIG. 6B, the developer G accumulated at the position on the upstream side of the developing gap is developed. It will gradually enter the gap little by little, so that the problem that the developer adheres to the developing roller 13a and the photosensitive drum 12 hardly occurs.
As described above, execution of the second drive mode returns to the normal state in which the normal image forming operation can be performed. In other words, when the second drive mode is executed, the state (agent reservoir) generated by the execution of the first drive mode returns to the normal state (state without agent reservoir) equivalent to that at the time of image formation. Become. That is, this "second drive mode" will function as the "agent accumulation removal mode", and after the second drive mode, as shown in FIG. 6C, return to the normal state where a normal image forming operation can be performed. 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 rotationally driven after the first drive mode (developer replenishment mode) using the image forming apparatus 1 according to the first embodiment. 7 shows experimental results of visual observation as to whether or not fixing of the developer occurred on the surface of the developing roller 13a and the photosensitive drum 12 for each combination. The experiment was conducted under the condition that the agent reservoir as shown in FIG. 6 (A) was generated.
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 the linear velocity B of 13a to be small (A> B), it was possible to confirm that the developer is prevented from adhering to the surface of the developing roller 13a and the photosensitive drum 12.

As described above, in the “second drive mode (agent accumulation removal mode)”, it is important to 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 at the development gap (opposite position) becomes larger than that at the time of image formation, and the linear velocity B of the development roller 13a at the development gap is at the time of image formation It can also be controlled to be equivalent to However, in that case, as the first drive motor 61, one that can increase the number of revolutions of the photosensitive drum 12 compared with that at the time of image formation is used, and the first drive motor 61 becomes large and expensive. It will be
On the other hand, in the first embodiment, as described above, the linear velocity of the photosensitive drum 12 in the development gap (opposite position) when the second drive mode (agent accumulation removal mode) is executed. Control is performed so that A becomes equal to that at the time of image formation, and the linear velocity B of the developing roller 13a in the development gap becomes smaller than that at the time of image formation. As a result, it is possible to prevent the developer from adhering to the surface of the developing roller 13a and the photosensitive drum 12 without increasing the size and cost of the first drive motor 61 and the second drive motor 62.

FIG. 9 is a graph showing a change in drive torque of the developing device 13 (second drive motor 62) after the start of the second drive mode. The drive torque is converted from the detection result by the current detection unit 63 (a measurement device that detects the current value flowing to the second drive motor 62) shown in FIG.
In FIG. 9, the solid line graph represents the state in which the developer G is accommodated in the developing device 13 (the state in which the first drive mode is normally executed), and the broken line graph represents the development in the developing device 13 as a comparison. It is a state in which the agent G is not contained (the one driven in an empty state without replenishing the developer). At 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 of the state in which the developer is stored is reduced and stabilized, and the time for the driving torque of the state in which the developer is not stored is reduced and stabilized. This is the difference between time and time, and this time N is the time required for the agent pool shown in FIG. 6A to be eliminated.
The inventor of the present invention measured the change of the drive torque of the developing device 13 shown in FIG. 9 according to the experimental conditions of FIG. It was confirmed that the time N in FIG. 9 becomes very short and close to 0 in the experimental condition in which no sticking occurs.

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 is not executed. The first drive motor 61 (the first drive motor 61) is set so that the linear velocity ratio X when the rotational drive of the photosensitive drum 12 is started along with the rotational drive of the first motor becomes equivalent to that at the time of image formation. Drive means and the second drive motor 62 (second drive means).
Specifically, in the first embodiment, the first drive mode is executed only when the developing device 13 is replenished with the developer, and only then is the second drive mode executed. And other start timings (only when the main power of the device 1 is turned on, when returning from the standby mode or the energy saving mode, when returning from the jam processing operation, or simply when the process control (image When the adjustment of the conditions is performed, etc.), the first drive mode and the second drive mode are not performed, and the photosensitive drum 12 and the developing roller 13a (normal speed ratio) are operated. Driving of the developing device 13) is started.
Further, as shown in FIG. 4, among the four process cartridges 10Y, 10M, 10C, and 10BK (developing devices 13), the one to which the developer G is to be replenished (the process cartridge 10BK for black). In the other process cartridges 10Y, 10M, and 10C (developing device 13), 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). The driving of the developing roller 13a (the developing device 13) is started. That is, the other process cartridges 10Y, 10M, and 10C which are not targets for replenishing the developer G are the ones for which the developer G is to be replenished (the process cartridge 10BK for black). While the first drive mode or the second drive mode is being performed, or thereafter, the photosensitive drum 12 and the developing roller 13a (developing device 13) are started to be driven at a normal linear velocity (linear velocity ratio) It will be.
By performing such control, it is possible to prevent a defect that the first drive mode or the second drive mode is executed needlessly.

Hereinafter, control when the developer G is replenished to the above-described developing device 13 will be collectively described using the flowchart shown in FIG.
As shown in FIG. 10, first, when the image forming apparatus 1 is started up, it is determined whether the developer G is replenished to the developing device 13 (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).
When it is determined that the developer G replenishment operation is performed on the developing device 13, the first drive mode (developer replenishment mode) is determined to be one in which the developer replenishment is 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 is finished, the second drive mode (agent reservoir removal mode) is executed for a predetermined time D2 (step S4).
Then, after the second drive mode is finished, process control (adjustment of image forming conditions) is performed while the developing device 13 and the photosensitive drum 12 are driven at normal speeds, respectively (step S5). Here, the process control is a known process performed after replenishing the developer, etc., and optically detects the image density of the patch pattern formed on the photosensitive drum 12 and the intermediate transfer belt 17. It calibrates the output value of the P sensor to be detected, and optimizes the values of the charging bias and the developing bias.
Then, after the process control is completed, the normal printing operation (image forming operation) is performed while the developing device 13 and the photosensitive drum 12 are driven at the normal speed, respectively (step S6).
If it is determined in step S1 that the developer G replenishment operation to the developing device 13 is not performed, the flow of steps S2 to S4 is not performed but the flow of steps S2 to S4 is performed. Will be
Thus, the present flow ends.

Here, in the first embodiment, the predetermined time D2 for executing the second drive mode is increased or decreased according to the increase or decrease of the time D1 for executing the first drive mode.
This is because when the time D1 in which the first drive mode is executed becomes long, the amount of agent accumulation shown in FIG. 6A also increases as compared with the case where the time D1 is short, so the second drive mode is executed. This is because it is necessary to set the time D2 long and to remove the agent pool reliably over time.
Therefore, for example, when the amount of developer replenished to four process cartridges 10Y, 10M, 10C, 10BK (developing device 13) is different, the replenishment to the process cartridge 10 in which the amount of developer replenished becomes large As compared with the process cartridge 10 in which the developer amount decreases, the time D1 for executing the first drive mode is set to be long, and the time D2 for executing the second drive mode is also set to be long accordingly. become.

Further, in the first embodiment, the time D2 for executing the second drive mode is set in advance as a constant.
On the other hand, as shown in FIG. 2, the current detection unit 63 (the current value flowing through the second drive motor 62) as a torque detection means for detecting the drive torque applied to the second drive motor 62 (second drive unit). When the driving torque detected by the current detecting unit 63 (torque detecting means) becomes smaller than a predetermined threshold value. It can also be controlled to end the 2 drive mode. It is possible to determine the state in which the agent reservoir has been removed from the change in drive torque applied to the second drive motor 62, as described above with reference to FIG. By performing such control, it is possible to efficiently and reliably remove the agent reservoir generated on the upstream side of the development gap.
In addition, it is possible to directly detect the agent accumulation generated on the upstream side of the development gap using a detection unit such as a photo sensor and control to end the second drive mode based on the detection result.

As described above, in the first embodiment, the first drive motor 61 is configured to rotationally drive the developing roller 13a in a state in which the rotational drive of the photosensitive drum 12 (image carrier) is stopped during non-image formation. When the “first drive mode” for controlling the (first drive means) and the second drive motor 62 (second drive means) is executed, the photosensitive drum 12 is added to the rotational drive of the developing roller 13a thereafter. So that the linear velocity ratio X (the 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) becomes smaller than 1. A "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 if the control for rotationally driving the developing roller 13a is performed in a state in which the rotational driving of the photosensitive drum 12 is stopped, when the photosensitive drum 12 is rotationally driven in addition to the developing roller 13a after the control. In addition, the developer G accumulated on the upstream side of the facing position of the photosensitive drum 12 and the developing roller 13a is stuck in the developing roller 13a or the photosensitive drum 12 as if it were put in favor so as to be in pressure contact with the facing position. Can be difficult to occur.

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

The image forming apparatus 1 in the second embodiment is also configured in substantially the same manner as that in the first embodiment, and in the same manner as in the first embodiment, the "first drive mode (developer replenishment mode)" After being executed, control is performed such that the "second drive mode (agent reservoir 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 at a predetermined contact pressure and a contact angle, and is carried on the surface of the photosensitive drum 12 A set detection unit 64 (refer to FIG. 2) is provided as a new article detection unit for detecting that the non-transferred toner thus formed is new.
In the first embodiment, the set detection unit 64 (new product detection means) stores various pieces of information such as an ID chip installed in the process cartridge 16 (use history regarding the process cartridge 16, date of manufacture, and the like. Is a reading device for reading information, and it is determined from the read information whether or not the cleaning blade 15 (process cartridge 16) is new.
The state where the cleaning blade 15 is new means that the cleaning blade 15 is not used at all as a member for performing the cleaning process, or is used only for a short time if it is used. Define.

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

More specifically, as shown in FIG. 11, when the second drive mode is being executed (when the developing device 13 is driven at low speed and the photosensitive drum 12 is driven at normal speed), writing is performed The 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 a predetermined toner image (toner for supplying to the cleaning blade 15 (The pattern as an image) is formed, and the toner image is passed through the primary transfer nip without being transferred to the intermediate transfer belt 17 at the primary transfer nip and supplied to the cleaning blade 15 (input ) To do. Therefore, when the "toner supply mode (blade protection mode)" is executed, the primary transfer bias applied to the primary transfer bias roller 20 is off (or a bias of the same polarity as the toner polarity is applied). ing).
In the second embodiment, the toner image (pattern is 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) forming a solid image of A4 size (320 mm.times.210 mm) as one pattern so that sufficient toner is supplied to the edge portion of the cleaning blade 15 in the width direction.

Such control is performed because the adhesion of the new cleaning blade 15 to the photosensitive drum 12 is too high, and the second drive mode is executed in the state as it is and the photosensitive drum 12 is rotationally driven. This is because the cleaning blade 15 may be shaken or chattering may occur.
On the other hand, in the second embodiment, when the cleaning blade 15 is new and the second drive mode is executed and the photosensitive drum 12 is rotationally driven, the toner image (on the photosensitive drum 12) The toner image is made to reach the edge portion of the cleaning blade 15 (the contact portion with the photosensitive drum 12). Therefore, the toner stagnates at the edge portion 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 loosened. Failures that cause chattering noise are surely reduced. That is, the "toner supply mode" functions as a "blade protection mode" for protecting the cleaning blade 15.

Further, 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 operated by the set detection unit 64 (new article detection means). When a new state is detected, the “second drive mode (agent reservoir removal mode)” is not executed, and a linear velocity ratio X2 (1 in the second embodiment) equivalent to that at the time of image formation. Control is performed so that the "toner supply mode (blade protection mode)" is executed.
Such control is performed when the second drive mode is not executed, when it is not necessary to set the linear velocity ratio X purposefully low, and the linear velocity ratio is set equal to that at the time of normal image formation. This is because the developing ability (the amount of toner adhesion per unit area of the toner image formed on the photosensitive drum 12) in the developing device 13 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, when only the “toner supply mode (blade protection mode)” is performed without performing the “second drive mode (agent reservoir removal mode)”, the second drive mode is formed on the photosensitive drum 12. As a toner image (pattern) to be formed, six patterns of solid images of A4 size (320 mm × 210 mm) 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 performed while the “second drive mode” is performed is A1. Assuming that the total area of the toner image developed by the developing device 13 when the second drive mode is not executed and the “toner supply mode” is executed is A2, the linear velocity ratio X in the second drive mode is X1 ( In the second embodiment, when the linear velocity ratio X at the time of image formation is X2, it is about 0.64).
A1 ≧ A2 × (X2 / X1)
Control to be established.
Specifically, as described above, the number of solid image patterns when the "toner supply mode" is performed while the "second drive mode" is performed is set to 15, and the total area A1 is 320 mm. The number of solid image patterns is set to 15 when the "toner supply mode" is executed without the "second drive mode" being executed, whereas the total area A2 is 320 mm. × 210 mm × 6 has become.

Such control is performed because, when the second drive mode is executed, the linear velocity ratio X of the developing roller 13a to the photosensitive drum 12 is set low, and the linear velocity ratio X is equal to that during normal image formation. Development capacity (toner adhesion amount per unit area of toner image formed on the photosensitive drum 12) in the developing device 13 becomes lower than when setting to It is because it becomes.
In the second embodiment, the number of patterns is increased to compensate for the decrease in the toner adhesion amount due to the decrease in the linear velocity ratio X in the second drive mode, and a sufficient toner amount is supplied to the new cleaning blade 15. As a result, it is possible to reliably reduce the problem that the cleaning blade 15 is shaken or chattering.

Hereinafter, control in the above-described second embodiment will be collectively described using the flowchart shown in FIG. The description of the steps common to the flowchart of FIG. 10 described above in the first embodiment will be omitted or simplified as appropriate.
As shown in FIG. 13, first, when the main power is turned on and the image forming apparatus 1 is started, it is determined whether the developer G is replenished to the developing device 13 (step S1). Step S1).
When it is determined that the developer G replenishment operation is performed on the developing device 13, the first drive mode (developer replenishment mode) is determined to be one in which the developer replenishment is completed. (Steps S2 and S3).
Then, after the end of the first drive mode, it is determined whether the cleaning blade 15 is new based on the detection result of the set detection unit 64 (step S13). As a result, when it is determined that the cleaning blade 15 is not a new one, the second drive mode (agent reservoir removal mode) is executed for a predetermined time D2 (step S4), and the flow from step S5 is performed.
On the other hand, when 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 removal mode). Then, the flow from step S5 is performed.

On the other hand, if it is determined in step S1 that the developer G has not been replenished to the developing device 13, the set detection unit 64 detects whether the cleaning blade 15 is new. It is determined based on the result (step S11). As a result, when it is determined that the cleaning blade 15 is not a new one, the flow from step S5 is performed.
On the other hand, when it is determined in step S11 that the cleaning blade 15 is new, the second drive mode (agent removal mode) is not performed, and the linear velocity ratio at the time of normal image formation is A toner supply mode (blade protection mode) is executed for a predetermined time in X (step S12), and the flow from step S5 is performed.

In the second embodiment, when the toner supply mode is executed, the toner image (pattern) formed in the developing step is set so that the application of the primary transfer bias to the primary transfer bias roller 20 is not performed. ) Is supplied to the cleaning blade 15 without being primarily transferred to the intermediate transfer belt 17.
On the other hand, the intermediate transfer belt 17 (primary transfer bias roller 20) can be separated from the photosensitive drum 12 by a known contact and separation mechanism, and when the toner supply mode is executed, The transfer belt 17 (primary transfer bias roller 20) is separated from the photosensitive drum 12, and the toner image (pattern) formed in the developing step is not primary-transferred onto the intermediate transfer belt 17, and is transferred to the cleaning blade 15. It can also be supplied.

As described above, in the second embodiment as well as the first embodiment, the developing roller 13a is stopped in the state where the rotational driving of the photosensitive drum 12 (image carrier) is stopped at the time of non-image formation. When the “first drive mode” for controlling the first drive motor 61 (first drive means) and the second drive motor 62 (second drive means) to rotationally drive the The linear velocity ratio X when the rotational driving of the photosensitive drum 12 is started in addition to the rotational driving of the photosensitive drum 12 (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 In the second drive mode, the first drive motor 61 and the second drive motor 62 are controlled such that the first drive motor 61 and the second drive motor 62 become smaller than one, for a predetermined time D2.
As a result, even if the control for rotationally driving the developing roller 13a is performed in a state in which the rotational driving of the photosensitive drum 12 is stopped, when the photosensitive drum 12 is rotationally driven in addition to the developing roller 13a after the control. In addition, the developer G accumulated on the upstream side of the facing position of the photosensitive drum 12 and the developing roller 13a is stuck in the developing roller 13a or the photosensitive drum 12 as if it were put in favor so as to be in pressure contact with the facing position. Can be difficult to occur.

In each of the above-described embodiments, the present invention is applied to the image forming apparatus 1 in which the developing device 13 is unitized with other imaging members as a component of the process cartridge 10. However, the application of the present invention is not limited to this, and the image forming member such as the developing device 13 is not formed as a process cartridge and configured to be detachably installed to the image forming apparatus as a single unit. Naturally, the present invention can be applied even if it is.
In the present application, “process cartridge” refers to 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 At least one of the cleaning units for cleaning the upper side and the image carrier are integrated and defined as a unit detachably installed in the image forming apparatus main body.

In each embodiment, one developing roller 13a is installed, two conveying screws as conveying members are installed in the vertical direction, and a doctor blade 13c is installed above the developing roller 13a. The present invention is 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 as to face the image carrier, a developing device in which two conveying screws are arranged in parallel in the horizontal direction, or three or more conveyances Naturally, the present invention is also applied to a developing device in which a screw is installed, a developing device in which a paddle roller is used as a conveying member, a developing device in which a doctor blade is installed below a developing roller, and the like. be able to.
Even in such a case, the same effect as that of each embodiment can be obtained.

Further, in each of the above embodiments, with the developing device 13 set in the image forming apparatus 1, the developer container 70 is set from the outside in a state where the main body door 100 is opened. The present invention is applied to an image forming apparatus that performs replenishment. On the other hand, as in the case of Patent Document 1, with the developing device set in the image forming apparatus, development is performed from a developer container (developer preset case) installed above the developing device with the main body door closed. Naturally, the present invention can be applied to an image forming apparatus for replenishing the developer to the apparatus.
Even in such a case, substantially the same effects as those of the above embodiments can be obtained.

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 and the transport 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 changed in multiple stages by the thick paper mode (low speed mode) or the like. Also in this case, by setting the first and second drive modes in accordance with the respective process linear speeds, it is possible to obtain the same effects as those of the respective embodiments.
Further, in each of the embodiments, the present invention is applied to an image forming apparatus in which the first drive mode is executed at the time of replenishment of the developer. However, the application of the present invention is not limited to this, and image formation is performed in which control (first drive mode) for rotationally driving the developing roller 13a in a state where rotation drive of the photosensitive drum 12 is stopped is performed at predetermined timing. If it is an apparatus (for example, an image forming apparatus that executes the first drive mode when a new developing apparatus is set in the image forming apparatus main body), the present invention can be applied to all of them. it can. And even in such a case, substantially the same effect as that of each embodiment can be obtained.

In each of the above embodiments, the present invention is applied to an image forming apparatus using a two-component developer composed of toner and carrier as a developer contained in the developing device 13. On the other hand, the present invention is also applicable to an image forming apparatus using a one-component developer (including the case of adding an additive etc.) consisting only of toner as a developer contained in the developing device. Can be applied. When a developing device of such a one-component developing system is used, in addition to a system in which the developing roller is opposed to the image carrier with a gap, a system 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 a co-rotation direction at the opposing position of the developing roller 13a and the photosensitive drum 12. did. On the other hand, the present invention can be applied to an image forming apparatus in which the developing roller and the photosensitive drum rotate in the counter direction at the facing position of the developing roller and the photosensitive drum.
And even in such a case, substantially the same effect as that of each embodiment can be obtained.

  The present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the above-described embodiments can be appropriately modified in addition to those suggested in the above-described embodiments. Is clear. Further, the number, position, shape and the like of the component members are not limited to those of the above-described embodiments, and the number, position, shape and the like suitable for practicing the present invention can be employed.

1 Image forming device (image forming device main body),
10, 10Y, 10M, 10C, 10BK process cartridge,
12 Photosensitive drum (image carrier),
13 Developer,
13a Development roller (developer carrier),
13c Doctor blade (developer regulation member),
14 charging device,
15 cleaning blades,
61 first drive motor (first drive means),
62 second drive motor (second drive means),
63 current detection unit (torque detection means),
64 sets detection unit (new item detection means),
G developer.

Patent No. 4695296 gazette JP, 2010-96923, A

Claims (14)

An image carrier rotationally driven in a predetermined direction by the first drive means;
The developer is accommodated in the inside, and the second driving means is rotationally driven in a predetermined direction such that the linear velocity ratio to the linear velocity of the image carrier at a position facing the image carrier becomes a predetermined value of 1 or more. A developing device provided with a developing roller for developing a latent image formed on the surface of the image bearing member;
Equipped with
At the time of non-image formation, a first drive mode is executed to control the first drive unit and the second drive unit so as to rotationally drive the developing roller while stopping the rotational drive of the image carrier. In the latter case, the first drive means and the second drive means are arranged such that the linear velocity ratio when the rotational drive of the image carrier is started in addition to the rotational drive of the developing roller is made smaller than 1 after that. An image forming apparatus characterized in that a second driving mode for controlling the image forming apparatus is executed for a predetermined time. A charging device which is charged with a charging bias to charge the surface of the image carrier;
When the first drive mode is executed, the charging device is controlled 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 apparatus according to claim 1, wherein when the second drive mode is executed, the charging device is applied with the charging bias and controlled so that 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 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 in which the said 2nd drive mode is performed is increased / decreased according to the increase / decrease of the time in which the said 1st drive mode is performed, The said 1st embodiment is characterized by the above-mentioned. Image forming apparatus.   The image forming apparatus according to any one of claims 1 to 4, wherein execution of the second drive mode returns to a normal state in which a normal image forming operation can be performed. A torque detection unit configured to detect a drive torque applied to the second drive unit;
The second drive mode is controlled to end when the drive torque detected by the torque detection means becomes smaller than a predetermined threshold value. The image forming apparatus according to claim 1.   At the time of non-image formation, when the first drive mode is not executed, the line when the rotational drive of the image carrier is started along with the rotational drive of the developing roller without executing the second drive mode The image forming apparatus according to any one of claims 1 to 6, wherein the first drive unit and the second drive unit are controlled such that a speed ratio becomes equal to that at the time of image formation. .   In the first drive mode, when the developing device and the image carrier are attached to the image forming apparatus, the inside of the developing device in which the developer contained therein is empty or is close thereto The image forming apparatus according to any one of claims 1 to 7, which is performed when the developer is filled in the toner. A cleaning blade that abuts on the image carrier to clean non-transferred toner carried on the surface of the image carrier;
New detection means for detecting that the cleaning blade is new;
Equipped with
The surface of the image carrier while the second drive mode is executed when the first drive mode is executed and the new article detection unit detects that the cleaning blade is a new article. The image forming method according to any one of claims 1 to 8, wherein a toner supply mode for supplying a toner to the cleaning blade is performed by developing the predetermined latent image formed on the surface by the developing device. apparatus.   When the first drive mode is not executed, and the second drive mode is not executed when the new article detection unit detects that the cleaning blade is a new article, at the time of image formation 10. The image forming apparatus according to claim 9, wherein the toner supply mode is executed at the same linear velocity ratio. If the total area of the toner image developed by the developing device when the toner supply mode is performed while the second drive mode is performed is A1, the toner supply mode is not performed. Assuming that 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 at the time of image formation is X2. ,
A1 ≧ A2 × (X2 / X1)
The image forming apparatus according to claim 10, wherein control is performed so as to establish the following relationship. The developing device comprises a developer regulating member for regulating the amount of developer carried on the surface of the developing roller above the developing roller.
The image carrier and the developing roller are both rotationally driven to move downward from above at the facing position,
The image forming apparatus according to any one of claims 1 to 11, wherein the developer is a two-component developer composed of a toner and a carrier. A process cartridge removably installed in an image forming apparatus, comprising:
An image carrier rotationally driven in a predetermined direction;
The developer is contained inside, and it is rotationally driven in a predetermined direction so that the linear velocity ratio to the linear velocity of the image carrier at a position facing the image carrier becomes a predetermined value of 1 or more, and the image carrier A developing device provided with a developing roller for developing a latent image formed on the surface of the body;
Equipped with
In addition to the rotational drive of the developing roller when the first drive mode for controlling the rotational drive of the developing roller is executed in a state where the rotational drive of the image carrier is stopped during non-image formation. A second drive mode for controlling the linear velocity ratio to be smaller than 1 when the rotational drive of the image carrier is started is executed for a predetermined time. And a cleaning blade for cleaning the non-transferred toner carried on the surface of the image carrier in contact with the image carrier.
When the first drive mode is executed, and the second drive mode is executed when the new article detection unit detects that the cleaning blade is new, the second drive mode is executed on the surface of the image carrier. 14. The process cartridge according to claim 13, wherein a toner supply mode for supplying a toner to the cleaning blade by developing the predetermined latent image formed by the developing device is executed.

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