JP6527373B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention is a developing device used in an image forming apparatus such as a copying machine, a printer, or a facsimile adopting an electrophotographic method, capable of stirring and conveying the developer and supplying it to the developing roller. The present invention relates to a developing device provided with a transport member.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a developer replenishment system is used in which a new developer is replenished when the developer is used for recording and consumed. As a developer replenishment system, a system in which a developer is replenished by replacing a detachable developer replenishment container in an image forming apparatus is used.

  In such an image forming apparatus, when part of the developer replenished from the developer replenishing container flows back to the developer replenishing container side, the developer accommodated in the developer replenishing container can not be used up. As a technique for preventing such a backflow, the developer supply container has an agitating member and a closing member inside, and with the rotation of the agitating member, the agitating blade rotates in advance of the closing member, and the closing member There is the one that rotates following the stirring blade. As a result, after the developer is sent toward the inner supply port by the stirring blade, the closing member following the stirring blade closes the inner supply port, and while the closing member closes the inner supply port, the developer is supplied to the developing chamber. Patent Document 1 proposes that the developer which has been introduced is prevented from flowing back into the developer supply container.

JP 2008-209758 A

  However, in the configuration described in Patent Document 1, the blocking member for backflow prevention is provided in the developer supply container to be replaced, and the running cost increases with the cost increase of the developer supply container. There is a problem of

  An object of the present invention is to prevent the backflow of the developer into the developer supply container without increasing the cost of the developer supply container to be replaced.

In order to achieve the above object, according to the present invention, there is provided a developer supply container containing a developer therein, an agitation chamber into which a developer supplied from the developer supply container flows from a replenishment port, and the agitation chamber A convex portion provided on the inner side, and including an upward surface adjacent to the supply port, the upward surface being a horizontal surface or a surface inclined toward the inside of the stirring chamber The developing device is configured of a portion and a stirring member which agitates the developer in the agitating chamber and abuts the upward surface of the convex portion during the operation of agitating the developer.

Schematic configuration of the image forming apparatus according to the present invention Control block diagram of image forming apparatus Schematic diagram of developing device Configuration diagram of conventional developing device Explanatory drawing of Example 1 A perspective view of the inside of the developing device of Example 1 Explanatory drawing of Example 2 Explanatory drawing of Example 3 Graph showing transition of developer remaining amount in conventional toner bottle Graph showing transition of residual amount of developer in toner bottle according to the present invention

  Hereinafter, embodiments of the present invention will be described based on the drawings.

  FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention, which includes an image reading apparatus 200 and an image forming apparatus 100.

In FIG. 1, the image reading apparatus 200 includes an image reading unit 210 that reads an image of a document, and a document feeding unit 220 that feeds a document D to the image reading unit 210.
In the image forming apparatus 100, a sheet feeding unit 10, an image forming unit 20, a fixing unit 30, and a sheet discharging unit 40 are provided in order from the lower part to the upper part. Further, on the right side of the image forming unit 20 and the fixing unit 30, a sheet re-feeding unit 50 is provided.

  The sheet feeding unit 10 feeds the sheet S stacked on the feeding cassette 11 or the manual feed tray 17 to the image forming unit 20. The sheet S stored in the feeding cassette 11 is fed to the separation roller pair 13 by rotation of the pickup roller 12. When the sheet S is double-fed, the sheet S is separated into one sheet by a separation roller pair 13 including a forward roller and a reverse roller, and is supplied to a feeding path PS1 indicated by a solid line.

Next, the sheet S is conveyed by the feed roller pair 15 to the registration roller pair 16. Here, the skew of the sheet S is corrected by causing the leading edge of the sheet S to conform to the nip of the resist roller pair 16 whose rotation is stopped. When the sheet S is fed from the multi sheet feeding tray 17, the sheet is separated into one sheet by the supply roller 18a and the separation pad 18b. Then, the sheet S is fed by being fed to the feed roller pair 15 by the feed roller pair 19 and conveyed to the registration roller pair 16 so that the skew of the sheet S is corrected.
The sheet whose skew has been corrected is conveyed to the image forming unit 20 by the registration roller pair 16 which rotates at a predetermined timing.

  In the image forming unit 20, the surface of the photosensitive drum 21 is uniformly charged by the charging roller 22. When the laser beam corresponding to the image information is irradiated from the laser unit 23, the portion of the photosensitive drum 21 irradiated with the laser beam is removed from the charge charged by the charging roller 22, and the electrostatic corresponding to the image information is generated. A latent image is formed. The electrostatic latent image formed here is attached with a developer by the developing roller 72 of the developing device 60 and is visualized as a developer image.

The developer image is conveyed to the transfer nip N1 by the rotation of the photosensitive drum 21. At this timing, the sheet S is conveyed from the registration roller pair 16 to the transfer nip N1. The conveyed sheet S is nipped and conveyed by the photosensitive drum 21 and the transfer roller 25 at the transfer nip portion N1. At this time, the developer image formed on the photosensitive drum 21 is transferred onto the sheet S by application of a bias voltage from the transfer roller 25. The laser beam emitted from the laser unit 23 is controlled based on the image data transmitted from the image reader 200 or the host PC 1.

  Next, the sheet S on which the developer image is formed is conveyed to the fixing unit 30. The fixing unit 30 includes a heat source such as a halogen lamp (not shown), a fixing roller 31, and a pressure roller 32. The fixing roller 31 is made of a material such as aluminum and heated to a predetermined temperature by a heat source. The pressure roller 32 is disposed in contact with the fixing roller 31 and is pressed with a predetermined pressure, and forms a fixing nip portion N2.

  The sheet S on which the developer image is formed is fed into the fixing nip portion N2, and nipped and conveyed by the fixing roller 31 and the pressure roller 32. At this time, the developer image is fixed on the sheet S by being heated and pressurized. The fixing unit 30 forms a fixing nip portion N2 by the pressure roller 32 pressing a heat source such as a ceramic heater via the endless film, in addition to the heating roller method of heating by the fixing roller 31. It is also possible to use an on-demand fixing method in which heating and pressing are performed while the sheet S is nipped and conveyed by the nip portion N2.

Next, the sheet S on which the developer image is fixed is conveyed to the sheet discharge unit 40 and discharged to the discharge tray 42 by the discharge roller pair 41.
When forming an image on both sides of the sheet S, when the sheet S on which the image is formed on the first side is conveyed by the discharge roller pair 41, the discharge roller is discharged before the rear end of the sheet S passes through the discharge roller pair 41 By temporarily stopping the pair 41 and further rotating the discharge roller pair 41 in reverse, the sheet S is reversed and conveyed to the sheet re-feeding unit 50.
The sheet S conveyed to the sheet re-feeding unit 50 is conveyed by the re-feeding roller pair 51a and 51b along the re-feeding path PS2 indicated by a broken line, and is conveyed to the registration roller pair 16 by the re-feeding roller pair 51 c. . Then, after the skew feeding is corrected by the registration roller pair 16, the back surface is conveyed to the transfer nip portion N1, whereby a developer image is formed on the second surface of the sheet S. Thereafter, the developer image is fixed to the sheet S by being conveyed through the fixing nip portion N2 in the same manner as when the image is formed on the surface, and the sheet S having the image formed on both sides is discharged by the discharge roller pair 41. Discharged into

FIG. 2 is a control block diagram of the image forming system of FIG. In FIG. 2, reference numeral 101 denotes a CPU as control means. The CPU 101 includes a RAM 102 used as storage of input data, a work storage area, and the like, and a ROM 103 storing programs such as control procedures. The CPU 101 is connected to the host PC 1 through the external interface 2 and performs reception of image data, transmission of apparatus status, and the like.
The CPU 101 controls an image reading device control unit 120 that controls the document reading operation and document feeding operation by the reading and scanning unit 250, an image signal processing unit 110 that processes an image signal from the image reading device control unit 120 or the host PC 1, It is connected to an image forming apparatus control unit 130 that forms an image on a sheet according to an image signal sent from the signal processing unit 110, an operation / display unit 140 that displays a message to a user as well as setting the main body.

FIG. 3 is a side sectional view of the conventional developing device 60. As shown in FIG.
In FIG. 3, the developing device 60 includes a developer supply container (hereinafter referred to as toner bottle) 90, a stirring chamber 80, and a developing chamber 70.

  The toner bottle 90 includes a bottle stirring and conveying member 91 inside. The bottle stirring and conveying member 91 is configured of a rotating shaft 91 a and a flexible sheet member 91 b. The rotation of the bottle stirring and conveying member 91 causes the toner T, which is the contained developer, to be stirred, and the toner is supplied to the stirring chamber 80 through the supply port 92. As the developer, magnetic one-component toner or the like is used.

The stirring chamber 80 is provided with a stirring chamber stirring and conveying member 81 inside. The stirring chamber stirring conveyance member 81 is composed of a rotary shaft 81a and a flexible sheet member 81b. As the stirring chamber stirring conveyance member 81 rotates, the toner T in the stirring chamber 80 is stirred and the toner is supplied to the developing chamber 70. In the stirring chamber 80, toner detection means 82 such as a magnetic permeability sensor is installed.
The toner detection unit 82 monitors the amount of toner in the stirring chamber 80. The bottle stirring and conveying member 91 and the stirring chamber stirring and conveying member 81 always rotate in conjunction with each other, and the output of the toner detection means 82 detects that the toner T in the stirring chamber 80 falls below a predetermined amount. The second CPU 101 determines that the amount of toner in the toner bottle 90 has decreased, and displays a message prompting the user to replace the toner bottle 90 on the operation display unit 140 of FIG.
A partition wall 83 is provided between the stirring chamber 80 and a developing chamber 70 described later.

  The developing chamber 70 internally includes a developing chamber stirring and conveying member 71, a developing roller 72, and a developer regulating member 73. The developing chamber stirring and conveying member 71 is composed of a rotary shaft 71a and an L-shaped metal plate 71b. The rotation of the developing chamber stirring and conveying member 71 causes the toner T in the developing chamber 70 to be stirred and the toner is supplied to the developing roller 72. The developing roller 72 is made of a magnetic material, carries the supplied toner, and conveys it to a developing area which is an area facing the photosensitive drum 21 in FIG. Then, a developing bias in which a DC voltage and an AC voltage are superimposed is applied to the developing roller 72, and the toner T is caused to fly from the developing roller 72 toward the photosensitive drum 21 of FIG. 1 to form an electrostatic latent image formed on the photosensitive drum 21. The toner T is attached to the toner to form a toner image. The developer regulating member 73 contacts the rotating developing roller 72, and keeps the thickness of the toner T carried on the surface constant.

FIG. 4 is an explanatory view of the operation of the developing device according to the conventional configuration. In FIGS. 4 to 8, a part of the configuration of the developing chamber 70 is omitted.
In FIG. 4, the toner is supplied from the toner bottle 90 to the stirring chamber 80 by the rotation of the bottle stirring and conveying member 91, and at the same time, the stirring chamber 80 is operated by the rotation of the stirring chamber stirring member 81 operating in conjunction with the bottle stirring and conveying member 91. The toner T is supplied to the developing chamber 70 from the above.

As shown in FIG. 4A, the toner T picked up by the stirring chamber stirring member 81 passes over the partition wall 83 and is supplied to the developing chamber 70. When the stirring chamber stirring member 81 further rotates, as shown in FIG. 4B, a part of the toner remains on the sheet member 81b of the stirring chamber stirring member 81 and becomes the staying toner T1.
As shown in FIG. 4C, the staying toner T1 is held between the inner wall of the agitating chamber 80 and the sheet member 81b by centrifugal force, and moves along the inner wall of the agitating chamber 80.
In FIG. 4D, when the agitating chamber agitating member 81 is further rotated and the sheet member 81b passes the supply port 92, the staying toner T1 is repelled downward by the restoring force of the bending of the sheet member 81b.
In FIG. 4E, the stagnant toner T1 which is bounced downward collides with the toner T accumulated at the bottom of the stirring chamber 80. At that time, in addition to the staying toner T1, the toner T at the bottom of the agitating chamber 80 is also scattered together. A part of the toner becomes backflow toner T 2 and flows back into the toner bottle 90 through the refill port 92.
With the rotation of the stirring chamber stirring member 81, the operations from FIG. 4 (a) to FIG. 4 (e) are repeated.

  FIG. 9 is a graph showing the relationship between the number of recording sheets and the remaining amount of toner in the toner bottle 90 in the developing device 60 according to the conventional configuration. In FIG. 9, when the number of recording sheets increases and the remaining amount of toner in the toner bottle 90 decreases, the decreasing rate of the remaining amount of toner in the toner bottle 90, that is, the inclination of the graph gradually becomes smaller. It shows a flat tendency.

This is because when the amount of toner in the toner bottle 90 decreases, the amount of replenishment of the toner T to the stirring chamber 80 by the rotation of the bottle stirring and conveying member 91 decreases. When the remaining amount of toner in the toner bottle 90 becomes less than a predetermined amount, the supply amount of toner T from the toner bottle 90 to the stirring chamber 80 becomes almost equal to the amount of backflow toner T2 flowing back from the stirring chamber 80 to the toner bottle 90. It becomes impossible to use up the toner T stored in the toner bottle 90.

FIG. 5 is an explanatory view of a developing device 60 according to this embodiment.
In FIG. 5A, a backflow prevention member 84 is provided adjacent to the replenishment port 92 on the inner wall of the developing chamber 80. When the staying toner T1 is repelled downward as shown in FIG. 5 (b), the staying toner T1 collides with the backflow preventing member 84 as shown in FIG. 5 (c). Since the staying toner T1 does not collide with the toner T at the bottom of the stirring chamber 80, the toner T at the bottom of the stirring chamber 80 does not scatter.
The shape of the upper surface of the backflow prevention member 84 can prevent backflow of the toner T to the toner bottle 90 through the supply port 92 if it is at least horizontal. In the present embodiment, the backflow prevention member 84 is provided with a slope toward the inside of the developing chamber 80, whereby when the staying toner T1 collides with the backflow prevention member 84, the backflow toner T2 passes through the replenishment port 92 as the backflow toner T2. It is possible to further reduce the backflow by scattering toward the bottle 90 side. When the agitating chamber agitating portion conveyance member 81 is further rotated and passes the replenishing port 92, the sheet member 81a contacts the backflow preventing member 84, but as shown in FIG. 5D, the sheet member 81a is flexible. Since it has, it is possible to deform and rotate as it is.

FIG. 6 is a perspective view of the replenishing port 92 inside the developing device of Embodiment 1 as viewed from the stirring chamber 80 side. In FIG. 6, the backflow prevention member 84 is installed so as to correspond to at least the opening of the replenishment port 92.
Although one supply port 92 is provided in this embodiment, a plurality of supply ports 92 may be provided. In such a case, the backflow prevention member 84 is disposed to correspond to the openings of the plurality of supply ports, whereby the backflow of the toner T to the toner bottle 90 through the supply port 92 can be prevented.

  FIG. 10 is a graph showing the relationship between the number of sheets to be recorded and the remaining amount of toner in the toner bottle 90 of the developing device 60 according to the configuration of this embodiment. In the developing device 60 according to this embodiment, since the backflow toner T2 generated at the time of operation is suppressed, as shown in FIG. 10, it is possible to reduce the remaining amount of toner in the toner bottle 90 when the graph becomes flat. It becomes possible.

By adopting the above configuration, it is possible to prevent the toner from flowing backward from the stirring chamber 80 to the toner bottle 90 through the supply port 92, and the configuration of the toner bottle 90 to be replaced is the same as the conventional one. As such, there is no rise in running costs.

  In the developing device 60 according to the first embodiment, the back wall prevention member 84 is provided on the inner wall of the agitating chamber 80 other than the position adjacent to the supply port 92.

FIG. 7 is an explanatory view of the back wall prevention member 84 provided on the inner wall of the stirring chamber 80 above the upper end of the supply port 92. In FIG. 7A, the staying toner T1 remaining on the sheet member 81b moves in response to the rotation of the stirring chamber agitating and conveying member 81, and when it reaches the position of FIG. 7B, contacts the backflow preventing member 84. Do. As shown in FIG. 7C, when the agitating chamber agitating and conveying member 81 is further rotated, the staying toner T1 is scraped off by the backflow preventing member 84. Since the stagnant toner T1 scraped off falls to a position away from the supply port 92, no toner backflow occurs. Further, since the sheet member 81b passes through the replenishing port 92 without the staying toner T1, the scattering of the toner T at the bottom of the stirring chamber 80 and the backflow of the toner to the toner bottle 90 do not occur.

  In the developing device 60 according to the first embodiment, the supply port 92 in which a valve member is installed as a backflow prevention member will be described.

FIG. 8 is an explanatory view of one in which the valve member 85 is installed on the inner wall of the stirring chamber. In FIG. 8A, the upper end of the valve member 85 is fixed to the upper portion of the supply port 92. The valve member 85 is larger than the supply port 92, and is configured as a flexible sheet. As shown in FIG. 8B, even if the staying toner T1 falls in the vicinity of the replenishing port 92 and collides with the toner T at the bottom of the agitating chamber 80, the replenishing port 92 is blocked by the valve member 85. No toner backflow to the bottle 90 occurs.
Further, as shown in FIG. 8C, at the timing when the bottle stirring and conveying member 91 rotates and the toner T is supplied to the stirring chamber 80, the toner T is pushed out of the supply port 92 by the sheet member 91a. Following the movement, the valve member 85 deforms toward the inside of the agitating chamber 80, and the shield of the supply port 92 is released.

In the present embodiment, the valve member 85 as the backflow prevention member is configured of a flexible sheet, but a plate-shaped member having a coaxial on the upper part of the supply port 92 and capable of rotating into the stirring chamber 80 It may be composed of
The present invention is not limited to the above embodiments, and any configuration may be applied as long as it has a configuration in which the backflow prevention member is provided on the stirring chamber 80 side.

1 host PC
60 developing device 70 developing chamber 71 developing chamber stirring conveyance member 71a rotary shaft 71b L-shaped sheet metal 72 developing roller 73 developer regulating member 80 stirring chamber 81 stirring chamber stirring conveyance member 81a rotary shaft 81b sheet member 82 toner detection means 83 partition wall 84 Backflow prevention member 85 Valve member T Toner 90 Toner bottle 91 Bottle stirring and conveying member 91a Rotation shaft 91b Sheet member 92 Refill port 100 Image forming apparatus 101 CPU
102 RAM
103 ROM
110 image signal control unit 120 image reading device control unit 121 CPU
122 RAM
123 ROM
124 I / O port 130 Image forming apparatus control unit 140 Operation and display unit 200 Image reading device 210 Image reading unit 220 Document feeding unit

Claims (2)

A developer supply container containing a developer inside;
An agitation chamber into which the developer supplied from the developer supply container flows from a supply port;
A convex portion convexly provided inside the stirring chamber , including an upward surface adjacent to the supply port, the upward surface being a horizontal surface or a surface inclined toward the inside of the stirring chamber A convex part,
A stirring member which abuts the upward surface of the convex portion during the operation of stirring the developer in the stirring chamber and stirring the developer;
A developing device characterized in that it comprises a. An image forming apparatus equipped with the developing device according to claim 1 .

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