JP2010061000A - Foreign material-removing/controlling apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove foreign materials caught between a regulating member and a developing roller without requiring a special mechanism. <P>SOLUTION: A motion-determining unit 84 determines whether or not a current state of a color printer 1 is in a motion state for non-image formation. When the motion-determining unit determines that the color printer 1 is in the operation state for non-image formation, a feed rate-adjusting unit 85 adjusts the feed rate of a developer that a supply roller 202 supplies to the developing roller 201, so that a higher amount of the developer than the feed rate of the developer to be supplied to the developing roller 201 at the time of the operation of image formation is supplied to the developing roller 201. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention restricts the thickness of a developer roller for supplying a developer from a supply member and supplying the developer to an image carrier, and a developer layer of the developer roller. The present invention relates to a foreign matter removal control device for removing foreign matter sandwiched between regulating members and an image forming apparatus including the foreign matter removal control device.

  An electrophotographic image forming apparatus includes an image forming unit capable of forming an image based on image information, a fixing unit capable of fixing an image formed by the image forming unit to paper, an image forming unit, a fixing unit, and the like. A paper transport unit that transports the paper to the functional unit and a discharge unit that discharges the paper on which the image is fixed to the outside of the image forming apparatus.

  In this image forming apparatus, the paper is transported to the image forming unit by the paper transport unit. An image is formed on the sheet conveyed by the sheet conveying unit in the image forming unit. The sheet on which the image is formed is conveyed to the fixing unit by the sheet conveying unit, and the image is fixed on the sheet in the fixing unit. Thereafter, the sheet on which the image is fixed is discharged from the discharge unit to the outside of the image forming apparatus.

  Here, the image forming unit generally has a photosensitive drum capable of carrying an electrostatic latent image on its surface and a developing device capable of supplying a developer to the photosensitive drum. In general, the developing device includes a developing roller disposed so as to face the photosensitive drum, a supply roller capable of supplying the developer to the developing roller, and a regulating member that regulates the layer thickness of the developer on the developing roller. And a developer container that can store the developer therein and supports the developing roller and the supply roller.

  In this image forming unit, an electrostatic latent image is formed on the photosensitive drum based on the image information. Then, the developer inside the developing container is supplied to the developing roller by the supply roller. Developer is supplied from the developing roller to the photosensitive drum, and a developer image is formed on the electrostatic latent image.

  By the way, in the image forming unit, dust or the like may enter the developing container, or foreign additives other than the toner may be contained in the developing container due to the external additive covering the surface of the toner being peeled off from the toner. In this case, there is a possibility that foreign matter together with the toner is supplied to the developing roller by the supply roller. When foreign matter is supplied to the developing roller together with the toner, the developing roller is conveyed to a position where the developing roller and the regulating member are in contact with each other by rotation of the developing roller. In some cases, foreign matter may be caught between the developing roller and the regulating member. As described above, when foreign matter is caught between the developing roller and the regulating member, the foreign matter prevents the toner layer from being uniformized.

  In order to solve such a problem, an image forming unit having a structure for changing the contact state of the regulating member to the developing roller is considered (see Patent Document 1).

  The image forming unit is provided with a cam that presses the regulating member toward the developing roller. As the cam rotates, the contact state of the regulating member to the developing roller is changed. Specifically, the regulating member is changed by the cam into a state in which the regulating member is in contact with the developing roller at the tip and a state in which the regulating member is in contact with the developing roller inside the tip. For this reason, when the tip of the regulating member is in contact with the developing roller, the foreign member sandwiched between the regulating member and the developing roller can be changed into a state in which the foreign member is in contact with the developing roller inside the tip. Thus, the foreign matter does not come into contact with the regulating member and is removed from the developing roller.

JP-A-8-227219

  In the apparatus described in Patent Document 1, it is necessary to provide a cam in the vicinity of the regulating member, and it is necessary to secure a space for arranging a mechanism using the cam in the apparatus. For this reason, the whole apparatus enlarges. Further, since a mechanism using a cam is installed, the cost increases.

  An object of the present invention is to remove a foreign matter sandwiched between a regulating member and a developing roller without providing a special mechanism.

  A foreign matter removal control device according to a first aspect of the present invention regulates the thickness of a developer roller that is supplied with a developer from a supply member of an image forming apparatus and supplies the developer to an image carrier, and a developer layer on the developer roller. A foreign matter removal control device for removing foreign matter sandwiched between regulating members, comprising an operation determining means and a supply amount adjusting means. The operation determining means is means for determining whether or not the current state of the image forming apparatus is a non-image forming operation state. The supply amount adjusting unit develops a larger amount of developer than the amount of developer supplied to the developing roller during the image forming operation when the operation determining unit determines that the image forming apparatus is in a non-image forming operation state. It is means for adjusting the amount of developer supplied to the developing roller of the supply member so as to be supplied to the roller.

  In this foreign matter removal control apparatus, it is determined whether or not the state of the image forming apparatus is in a state where an image forming operation is being performed. When it is determined that the image forming apparatus is not in an image forming operation, a larger amount of developer is supplied to the developing roller than the amount of developer supplied to the developing roller during the image forming operation. In this way, the amount of developer supplied to the developing roller of the supply member is adjusted. When a foreign object is sandwiched between the developing roller and the regulating member, the regulating member is deformed in a direction away from the developing roller by the developer supplied to the developing roller. At this time, the force sandwiched between the developing roller and the regulating member that has acted on the foreign matter is released. For this reason, the foreign matter can be removed from between the developing roller and the regulating member.

  Here, the foreign matter sandwiched between the developing roller and the regulating member can be removed. Further, it is not necessary to provide a special mechanism for removing foreign matters, and an increase in size due to the provision of the special mechanism can be prevented. Further, the cost for providing the foreign matter removing mechanism is unnecessary, and the cost of the apparatus can be prevented from increasing.

  A foreign matter removal control device according to a second aspect is the foreign matter removal control device according to the first aspect, wherein when the developer is supplied from the supply member to the development roller, an AC bias is applied to the development roller and the supply member, respectively. Applied. The supply amount adjusting means adjusts at least one of the AC bias applied to the supply member and the AC bias applied to the developing roller to increase the developer supply amount to the developing roller.

  Here, the developer supply amount to the developing roller can be increased by adjusting at least one of the AC bias applied to the supply member and the AC bias applied to the developing roller. Further, since the amount of developer supplied is adjusted by adjusting the applied AC bias, it is not necessary to provide a special mechanism for increasing the developer supply amount. For this reason, it can prevent that an apparatus enlarges. Moreover, the increase in cost accompanying providing a special mechanism can be prevented. Here, the AC bias means a DC voltage superimposed with an AC voltage.

  A foreign matter removal control device according to a third aspect is the foreign matter removal control device according to the second aspect, wherein the supply amount adjusting means is applied to the developing roller so that the developer is easily supplied from the supply member to the developing roller. At least one of the AC bias and the AC bias applied to the supply member is adjusted.

  A foreign matter removal control apparatus according to a fourth aspect of the present invention is the foreign matter removal control device according to the second or third aspect, further comprising a printed sheet number calculating unit that calculates the number of printed sheets and a storage unit that stores a threshold value regarding the number of printed sheets. Yes. The operation determining unit determines the current state of the image forming apparatus when the number of printed sheets calculated by the printed sheet number calculating unit exceeds a threshold stored in the storage unit.

  This foreign matter removal control apparatus calculates the number of printed sheets and determines whether the number of printed sheets exceeds a threshold value. When the number of printed sheets exceeds the threshold value, the operation of the image forming apparatus is determined by the operation determination.

  A foreign matter removal control device according to a fifth aspect is the foreign matter removal control device according to any one of the second to fourth aspects, wherein the supply amount adjusting means uses an effective bias for the supply member of the developing roller as an effective bias during an image forming operation. At least one of the AC bias applied to the developing roller and the AC bias applied to the supply member is controlled to be larger.

  Here, the amount of developer supplied from the supply member to the developing roller can be increased. Here, the effective bias is a difference A between an AC bias applied to the supply member and an AC bias applied to the developing roller, and an AC bias applied to the supply member and an AC bias applied to the developing roller. This is the product of time B (Duty) when difference A occurs. For example, it refers to the portion C in FIG. 6 and the portion D in FIG. Here, FIG. 6 is a diagram showing the AC bias E having a waveform as shown in FIG. 4 applied to the developing roller and the AC bias F having a waveform as shown in FIG. 5 applied to the supply roller. FIG. 8 is a diagram showing an AC bias E having a waveform as shown in FIG. 4 applied to the developing roller and an AC bias G having a waveform as shown in FIG. 7 applied to the supply roller.

  An image forming apparatus according to a sixth aspect includes an image carrier, a developing device, and a foreign matter removal control device. The image carrier is a member capable of carrying an image on the surface. The developing device includes a developing roller disposed so as to face the image carrier, a supply member capable of supplying a developer to the developing roller, and a regulating member that regulates the layer thickness of the developer on the developing roller. . The foreign matter removal control device is a device according to any one of claims 1 to 5.

  In this image forming apparatus, an electrostatic latent image is formed on an image carrier based on image information. Then, developer is supplied from the developing device to the electrostatic latent image, and an image is formed on the image carrier.

  An image forming apparatus according to a seventh aspect is the image forming apparatus according to the sixth aspect, wherein the developing device further includes a developing container for storing a one-component developer.

  Here, when a one-component developer is used, it is generally necessary to charge the toner by a regulating member. For this reason, the regulating member is in contact with the developing roller, and foreign matter is likely to be caught between the developing roller and the regulating member. Therefore, in the case of an image forming apparatus using a one-component developer, this case is further effective.

  An image forming apparatus according to an eighth aspect is the image forming apparatus according to the sixth or seventh aspect, wherein the regulating member is disposed so as to contact the developing roller.

  Here, when the regulating member is in contact with the developing roller, foreign matter is likely to be caught between the developing roller and the regulating member. For this reason, the present invention is more effective in such a case.

  In the present invention, it is possible to remove foreign matter sandwiched between the regulating member and the developing roller without providing a special mechanism.

[overall structure]
A color printer 1 as an image forming apparatus according to the present invention will be described below with reference to FIG. Here, FIG. 1 shows an overall outline of a color printer 1 according to the present invention. The color printer 1 is connected to an external computer or the like, and can form an image on a sheet based on image information sent from the computer. In the color printer 1, in the image forming operation, the toner is negatively charged and the photosensitive drum 21 described later is also negatively charged.

  As shown in FIG. 1, the color printer 1 includes an image forming unit 2, a transfer unit 3, a paper storage unit 4, a paper transport unit 5, a fixing unit 6, a discharge unit 7, and a foreign matter removal control device 8. (See FIG. 8). The configuration of each functional unit will be described below. The foreign matter removal control device 8 will be described in detail later.

{Image forming part}
The image forming unit 2 is a part for forming an image on a sheet based on image information. The image forming unit 2 includes a photosensitive drum 21 (image carrier), a rotary developing device 22, a charging device 23, a laser unit 24, a first AC bias applying device 25 (see FIG. 2), and a second AC. And a bias applying device 26 (see FIG. 2).

  The photosensitive drum 21 is a member capable of carrying an electrostatic latent image on the surface. In addition, the photosensitive drum 21 is disposed substantially at the center of the apparatus. The photosensitive drum 21 has a rotation shaft extending in a direction orthogonal to the paper surface of FIG.

  The rotary developing device 22 is a device for supplying toner of each color to the photosensitive drum 21. Further, the rotary developing device 22 is disposed adjacent to the photosensitive drum 21. Further, the rotary developing device 22 is a substantially cylindrical device. The rotary developing device 22 includes a rotary shaft 221 that extends in a direction orthogonal to the paper surface of FIG. 1, a frame 222, and four developing devices 20. The developing device 20 will be described in detail later.

  The frame 222 is a member for supporting the four developing devices 20. The frame 222 has four plate-like members 222 a arranged at equal intervals around the rotation shaft 221. The frame 222 is a member that is rotated in the direction of arrow A in FIG.

  The charging device 23 is a device for uniformly charging the surface of the photosensitive drum 21. The charging device 23 is disposed below the photosensitive drum 21.

  The laser unit 24 is a device for irradiating the surface of the photosensitive drum 21 with laser light based on image information. The laser unit 24 is disposed below the rotary developing device 22.

  A first AC bias applying device 25 shown in FIG. 2 is a device for applying an AC bias to the developing roller 201 described later. The first AC bias applying device 25 is connected to a developing roller 201 described later. The first AC bias applying device 25 applies an AC bias during the image forming operation and the foreign matter removing operation. Specifically, the first AC bias applying device 25 applies an AC bias having a waveform as shown in FIG. 4 to the developing roller 201 described later.

  A second AC bias applying device 26 shown in FIG. 2 is a device for applying an AC bias to a supply roller 202 described later. The second AC bias application device 26 is connected to the supply roller 202. Further, the second AC bias applying device 26 applies an AC bias during the image forming operation and the foreign matter removing operation. Specifically, the second AC bias applying device 26 applies an AC bias having a waveform as shown in FIG.

  An AC bias E as shown in FIG. 4 is applied to the developing roller 201 described later by the first AC bias applying device 25, and an AC bias F having a waveform as shown in FIG. Therefore, an effective bias as shown by C in FIG. 6 acts between the developing roller 201 and the supply roller 202. FIG. 6 shows the AC bias E applied to the developing roller 201 and the AC bias F applied to the supply roller 202 simultaneously during the image forming operation.

  Here, the effective bias is the difference A between the AC bias F applied to the supply roller 202 and the AC bias E applied to the developing roller 201, and the AC bias F applied to the supply roller 202 and the developing roller 201. It means the product of the time B (Duty) in which the difference A from the applied AC bias E occurs.

{Transcription part}
The transfer unit 3 includes a transfer belt 31, a primary transfer roller 32, a secondary transfer roller 33, and four belt support rollers 34.

  The transfer belt 31 is a member for transferring an image formed by the image forming unit 2 to a sheet. The transfer belt 31 is a member to which an image is primarily transferred from the photosensitive drum 21. Further, the transfer belt 31 is disposed on the upper side of the photosensitive drum 21.

  The primary transfer roller 32 is a member for transferring the image on the photosensitive drum 21 onto the transfer belt 31. The primary transfer roller 32 is disposed so as to face the photosensitive drum 21 with the transfer belt 31 interposed therebetween. Further, each primary transfer roller 32 is connected to a voltage application device (not shown).

  The secondary transfer roller 33 is a member for transferring an image from the transfer belt 31 to a sheet. The secondary transfer roller 33 is disposed so as to face the transfer belt 31 with the paper transport path of the paper transport unit 5 interposed therebetween.

  The four belt support rollers 34 are rollers for supporting the belt. A predetermined tension is applied to the transfer belt 31 by the four belt support rollers 34.

{Paper storage}
The paper storage unit 4 is a part for storing paper. In addition, the paper storage unit 4 is disposed below the color printer 1. Further, the paper storage unit 4 has a paper feed cassette 41 that can store paper.

{Paper transport section}
The paper transport unit 5 is a part for transporting paper to each functional unit. The paper transport unit 5 has a paper transport path for transporting paper in the order of the paper storage unit 4, the transfer unit 3, the fixing unit 6, and the discharge unit 7. The paper transport unit 5 includes a paper transport guide pair 51 and a plurality of paper transport roller pairs 52.

  The paper transport guide pair 51 is a member for guiding the paper transport direction. The paper transport guide pair 51 has plate-like members arranged so as to face each other. A sheet can pass between these plate-like members.

  The paper transport roller pair 52 is a member for transporting paper in the paper transport direction. The pair of paper transport rollers 52 has two rollers arranged to face each other. The sheet can pass between the two rollers.

{Fixing part}
The fixing unit 6 is a part for fixing an image on a sheet. The fixing unit 6 is disposed on the downstream side of the transfer unit in the sheet conveyance direction. Further, the fixing unit 6 includes a heating roller 61 that heats the image, and a pressure roller 62 that is disposed to face the heating roller 61 and presses the paper between the heating roller 61.

{Discharge unit}
The discharge unit 7 is a part for discharging the paper to the outside of the color printer 1. As shown in FIG. 1, the discharge unit 7 is disposed downstream of the fixing unit 6 in the sheet conveyance direction.

[Developer]
The four developing devices 20 are devices for supplying different color toners to the photosensitive drum 21. The developing device 20 is supported by the frame 222. As shown in FIG. 2, the developing device 20 includes a developing roller 201, a supply roller 202, a developing container 203, and a layer thickness regulating blade 204. FIG. 2 is an enlarged sectional view of the developing device 20. Since the four developing devices 20 have the same configuration, only one developing device 20 is shown in FIG.

  The developing roller 201 is provided at a position that can face the photosensitive drum 21. Further, the developing roller 201 has a rotating shaft extending in a direction orthogonal to the paper surface of FIG.

  The supply roller 202 is a member for supplying the developer in the developing container 203 to the developing roller 201. Further, the supply roller 202 is disposed so as to contact the developing roller 201. Further, the supply roller 202 is disposed inside the developing container 203. The supply roller 203 is a roller formed by covering the surface of a metal cored bar with a conductive elastic foam material.

  The developing container 203 is a member for accommodating a one-component developer therein. Further, the developing container 203 has a partition plate 203a that divides the developing container 203 into two spaces, and an opening 203b in which the developing roller 201 can be disposed and extends in a direction perpendicular to the paper surface of FIG. The four developing containers 203 shown in FIG. 1 contain yellow, cyan, magenta, and black developers, respectively.

  The layer thickness regulating blade 204 is a member for regulating the layer thickness of the developer attached to the surface of the developing roller 201. The layer thickness regulating blade 204 is a plate-like member. The layer thickness regulating blade 204 is fixed to the developing container 203 with bolts. Further, the layer thickness regulating blade 204 is disposed at a position where it can contact the developing roller 203.

[Foreign substance removal control device]
The foreign matter removal control device 8 is a device for controlling the AC bias applied to the supply roller 202. The foreign matter removal control device 8 controls the second AC bias applying device 26 when performing the operation of removing the foreign matter on the developing roller 201. FIG. 3 shows a block diagram of the foreign matter removal control device 8. Hereinafter, the foreign matter removal control device 8 will be described with reference to the block diagram of FIG.

  The foreign matter removal control device 8 includes a storage unit 81 (storage means) and a CPU. The foreign matter removal control device 8 includes a print number calculation unit 82 (print number calculation unit), a timing determination unit 83, an operation determination unit 84 (operation determination unit), a supply amount adjustment unit 85 (supply amount adjustment unit), It has. Further, the foreign substance removal control device 8 is a device that can control each functional unit by executing a program.

  The storage unit 81 is a part in which various programs for controlling the functional unit are stored. The storage unit 81 stores a threshold value for the number of printed sheets. This threshold value is for determining the timing for performing the foreign substance removal operation. Specifically, the threshold is 100 sheets.

  The number-of-printing-number calculating unit 82 is a part for calculating the number of printed sheets from a point in time when a foreign substance removing operation described later is completed.

  The timing determination unit 83 is a part for determining the timing for performing the foreign substance removal operation. Specifically, it is determined whether or not the number of printed sheets exceeds a threshold value, and the time when the job being performed when the number exceeds the threshold value is determined as the timing of the foreign substance removal operation.

  The operation determination unit 84 is a unit that determines whether the current state of the color printer 1 is a non-image forming operation state.

  The supply amount adjustment unit 85 controls the AC bias applied to the supply roller 202 from the second AC bias application device 26 when the operation determination unit 84 determines that the color printer 1 is in the non-image forming operation state. Specifically, the second AC bias application device 26 is controlled such that an AC bias G as shown in FIG. 7 is applied to the supply roller 202. That is, the second AC bias is applied so that an AC bias having the same waveform as that of the AC bias applied to the developing roller 201 of the AC bias during the image forming operation is applied to the supply roller 202. The device 26 is controlled. Therefore, an effective bias represented by a portion D in FIG. 8 acts between the developing roller 201 and the supply roller 202.

  FIG. 9 shows the relationship between the amount of developer supplied from the supply roller 202 to the developing roller 201 and the effective bias. As is clear from FIG. 9, when the effective bias increases, the amount of developer supplied from the supply roller 202 to the developing roller 201 increases.

[Operation]
Next, the operation of the color printer 1 will be described.

  When image information is sent from a computer connected to the outside of the color printer 1, an electrostatic latent image is formed on the photosensitive drum 21 based on the image information. Specifically, the surface of the photosensitive drum 21 is charged by the charging device 23, and the photosensitive drum 21 is irradiated with laser light from the laser unit 24 based on the image information.

  When the electrostatic latent image is formed on the photosensitive drum 21 in this way, toner is supplied from the developing roller 201 of each developing device 20 to the electrostatic latent image. Specifically, after the first color developer is supplied from the developing device 20 onto the photosensitive drum 21, the frame 222 rotates about 90 degrees about the rotation shaft 221. At this time, the developing roller 201 of the developing device 20 containing the developer for the second color faces the photosensitive drum 21. Then, a second color developer is supplied from the developing roller 201 onto the photosensitive drum 21. The same operation is repeated and all the four color developers are supplied to the photosensitive drum 21.

  Then, the toner image on the photosensitive drum 21 is transferred to the transfer belt 31 while being superimposed. The toner image on the transfer belt 31 is transferred to a sheet. The sheet on which the toner image is transferred is conveyed to the fixing unit 6 by the sheet conveying unit 5. After the toner image is fixed on the sheet by the fixing unit 6, the toner image is conveyed to the discharge unit 7. The sheet conveyed to the discharge unit 7 is discharged out of the color printer 1.

[Foreign substance removal control operation]
First, it is determined whether the number of printed sheets has exceeded 100 (S1). If the number of printed sheets does not exceed 100 (NO in S1), the process waits until the number exceeds 100. On the other hand, if it exceeds 100 sheets (YES in S1), it is determined whether or not the current state of the color printer 1 is an image forming operation (S2). When the color printer 1 is performing an image forming operation (NO in S2), the process waits until the image forming operation is completed. On the other hand, when the image forming operation is not performed in the color printer 1 (YES in S2), the foreign matter removing operation is performed (S3).

  Specifically, the AC bias E shown in FIG. 4 is applied to the developing roller 201 by the first AC bias applying device 25, and the AC bias G shown in FIG. 7 is applied to the supply roller 202 by the second AC bias applying device 26. Applied. Then, the developer is supplied to the developing roller 201 by the supply roller 202 to which the AC bias G shown in FIG. 7 is applied. The developing roller 201 is rotated several times while supplying the developer. Specifically, the developing roller 201 is rotated about 5 times. At this time, the layer thickness regulating blade 204 is pushed and spread in a direction away from the developing roller 201 by the developer attached to the developing roller 201. The foreign matter sandwiched between the developing roller 201 and the layer thickness regulating blade 204 is separated from the layer thickness regulating blade 204, and the foreign matter is removed from the developing roller 201. Then, the number of printed sheets is reset (S4).

[effect]
Here, the foreign matter sandwiched between the developing roller 201 and the layer thickness regulating blade 204 can be removed by the foreign matter removing operation. For this reason, it is possible to prevent the developer layer on the developing roller 201 from becoming non-uniform due to the foreign matter, and to prevent the image quality from deteriorating. And since it is not necessary to provide the mechanism for foreign material removal, it can prevent that an apparatus enlarges. The cost required to install the foreign matter removal mechanism is eliminated. For this reason, it can prevent that manufacturing cost becomes high. Further, since the foreign matter removing operation is performed during the non-image forming operation, the image forming operation is not hindered and the printing efficiency can be prevented from being lowered.

[Other Embodiments]
(A) In the above embodiment, the AC bias applied to the supply roller 202 is controlled in order to increase the amount of developer supplied from the supply roller 202 to the developing roller 201. However, the present invention is not limited to this. The developer supply amount may be increased by other methods. For example, the developer supply amount to the developing roller 201 may be increased by increasing the rotation speed of the supply roller 202.

  (B) In the above-described embodiment, the foreign matter removing operation is performed every 100 sheets. However, the present invention is not limited to this, and may be other numbers, for example, every 200 sheets or every 500 sheets. Further, a foreign substance may be detected by a sensor or the like to perform a foreign substance removal operation.

  (C) Furthermore, in the above embodiment, the color printer 1 has been described. However, the present invention is not limited to this, and may be a copying machine, a multifunction machine, or the like.

  (D) In the above embodiment, the AC bias applied to the supply roller 202 is controlled. However, the present invention is not limited to this, and the AC bias applied to the developing roller 201 may be controlled. Further, both the AC bias applied to the developing roller 201 and the AC bias applied to the supply roller 202 may be controlled.

  (E) In the above embodiment, the effective bias shown in FIG. 8 acts between the developing roller 201 and the supply roller 202. However, the present invention is not limited to this. For example, the effective bias shown in FIG. May act between the supply roller 202 and the developing roller 201.

  (F) In the above embodiment, the color printer 1 using a one-component developer has been described. However, the present invention is not limited to this, and an apparatus using a two-component developer may be used.

1 is an overall schematic cross-sectional view of a multifunction machine according to an embodiment of the present invention. The expanded sectional view of a developing device. The block diagram which shows a foreign material removal control apparatus. FIG. 4 is a diagram illustrating a waveform of an AC bias applied to a developing roller during an image forming operation. The figure which shows the waveform of the alternating current bias applied to a supply roller at the time of image forming operation. The figure which shows the effective bias at the time of image formation operation | movement. The figure which shows the waveform of the alternating current bias applied to a supply roller at the time of a foreign material removal operation | movement. The figure which shows the effective bias at the time of a foreign material removal operation | movement. The figure which shows the relationship between the developer supplied to a developing roller, and an effective bias. The figure which shows the flowchart of a foreign material removal operation | movement. The figure which shows the effective bias at the time of the foreign material removal operation | movement in other embodiment.

Explanation of symbols

1 Color printer (image forming device)
8 Foreign object removal control device 21 Photosensitive drum (image carrier)
81 Storage section (storage means)
82 Number-of-printing-number calculating section (number-of-printing-number calculating means)
84 Operation determination unit (operation determination means)
85 Supply amount adjustment unit (Supply amount adjustment means)
201 Developing roller 202 Supply roller (supply member)
203 Developing container 204 Layer thickness regulating blade (regulating member)

Claims (8)

Foreign matter sandwiched between a developing roller for supplying the developer from the supply member of the image forming apparatus and supplying the developer to the image carrier and a regulating member for regulating the thickness of the developer layer on the developing roller A foreign matter removal control device for removing
Operation determining means for determining whether the current state of the image forming apparatus is a non-image forming operation state;
When the operation determining unit determines that the image forming apparatus is in a non-image forming operation state, a larger amount of developer is supplied to the developing roller than the amount of developer supplied to the developing roller during the image forming operation. A supply amount adjusting means for adjusting a developer supply amount of the supply member to the developing roller so as to supply;
Foreign matter removal control device. When the developer is supplied from the supply member to the development roller, an AC bias is applied to the development roller and the supply member,
The supply amount adjusting means adjusts at least one of an AC bias applied to the supply member and an AC bias applied to the developing roller to increase a developer supply amount to the developing roller;
The foreign matter removal control apparatus according to claim 1. The supply amount adjusting means adjusts at least one of an AC bias applied to the supply member and an AC bias applied to the development roller so that the developer is easily supplied from the supply member to the development roller. ,
The foreign matter removal control device according to claim 2. A printed sheet number calculating means for calculating a printed sheet number;
Storage means for storing a threshold relating to the number of printed sheets,
The operation determining unit determines a current state of the image forming apparatus when the number of printed sheets calculated by the printed sheet number calculating unit exceeds a threshold stored in the storage unit;
The foreign matter removal control device according to claim 2 or 3. The supply amount adjusting unit includes an AC bias applied to the developing roller and an AC applied to the supply member so that an effective bias of the developing roller with respect to the supply member is larger than the effective bias during an image forming operation. Control at least one of the bias,
The foreign matter removal control apparatus according to claim 2. An image carrier capable of carrying an image on the surface;
A developing roller disposed so as to face the image carrier, a supply member capable of supplying a developer to the developing roller, and a regulating member for regulating a thickness of the developer layer on the developing roller. A developing device;
The foreign matter removal control device according to any one of claims 1 to 5,
An image forming apparatus.   The image forming apparatus according to claim 6, wherein the developing device further includes a developing container for storing a one-component developer.   The image forming apparatus according to claim 6, wherein the regulating member is disposed so as to contact the developing roller.

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