JP5343632B2 - Developing device and image forming apparatus using the same - Google Patents

Description

  The present invention is used in an image forming apparatus such as a monochrome / color electrophotographic copying machine, a laser printer, a FAX, or an MFP, and develops an electrostatic latent image formed on a photosensitive drum with toner. The present invention relates to a developing device using a two-component developing method using a carrier and employing a torquel method.

  Conventionally, it is known that the two-component development method used for the electrophotographic development method has less image deterioration and better durability than other development methods. However, as the use of this two-component development system progresses, the toner withstand voltage performance of the carrier decreases due to toner adhesion to the carrier in the developer and wear of the coating layer applied to the carrier surface. Image degradation such as background fogging occurs.

  Therefore, it is possible to employ a so-called torquel method in which, when toner is replenished, the toner is replenished in a state where the carrier is mixed in an amount of 5 to 40 wt%, and the developer remaining in the developing trough is discharged little by little. According to this method, since a certain amount of carrier is replenished together with the toner and replaced at a certain rate with the used carrier in the developing basket, it is much longer than a normal two-component developing method other than the torquer method. Meanwhile, there is an advantage that no image defect occurs.

  On the other hand, in the torquer system, excess developer is often discharged by overflowing from a discharge port provided in the developing trough, and the developer discharge amount is constant depending on the installation state of the apparatus. However, there was a problem that the amount of the developer in the developing trough was too large or too small.

  In order to keep the developer discharge amount constant, for example, Patent Document 1 describes a developing device in which a developer overflow outlet is provided at a position corresponding to the center of a leg portion that supports the image forming apparatus main body.

  Further, Patent Document 2 describes a developing device provided with a developer discharging port at both ends of a developing rod and a reflux mechanism that returns the developer discharged from the two developer discharging ports into the developing rod. Has been.

  However, in the developing device described in Patent Document 1, since the center of the leg portion and the center of the developing device do not coincide with each other, even if an overflow outlet is provided at the center of the leg portion, the image forming apparatus has an inner portion depending on the tilting direction. There was a problem that the amount of developer increased.

  In the developing device described in Patent Document 2, since the reflux mechanism portion is provided in the developing device, the structure of the developing device becomes complicated and the manufacturing cost increases.

Japanese Patent No. 3034736 JP2007-102098

  The present invention has been made in view of the above-described conventional problems, and a developing device capable of preventing an increase in the amount of developer in the developing device with a simple configuration, and an image forming apparatus using the same. It is an issue to provide.

In order to solve the above problems, a developing device according to the present invention provides:
A developer containing container for containing the developer, a developing roller for carrying the developer in the developer containing container and adhering the toner to the photosensitive drum, and in the developer containing container while stirring the developer. A stirring screw for circulating the developer, a supply screw for supplying the developer circulated by the stirring screw to the developing roller, a replenishing port for replenishing the developer in the developer containing container, and a developer containing container In a developing device having a first discharge port provided at an end portion on the same side as the supply port, and discharging a circulating developer,
A second discharge port is provided at the end of the developer container opposite to the first discharge port,
The second discharge port is disposed opposite to a sealing pole that prevents leakage of the developer out of the developer container among the magnetic poles of the magnetic material provided inside the developing roller. A discharge agent storage section for storing the developer,
The discharge agent storage portion is attached to the outer surface of the developer storage container so as to cover the second discharge port .

  By providing the second discharge port at the end opposite to the first discharge port of the developer container, the developer is not discharged from the first discharge port by tilting the developing device, and the developer container Even if the developer amount increases, the developer is discharged from the second discharge port. Therefore, it is possible to prevent the developer amount in the developer container from increasing.

  Further, since the second discharge port is only provided at the end opposite to the first discharge port of the developer container, it is possible to prevent the developer amount in the developing device from increasing with a simple configuration.

  Since the second discharge port includes the discharge agent storage unit, the developer discharged from the second discharge port is stored in the discharge agent storage unit. Therefore, it is possible to prevent the developer discharged from the second discharge port from leaking out of the developing device and contaminating the inside of the apparatus main body.

The second discharge port is disposed to face a sealing pole that prevents the developer from leaking out of the developer container among the magnetic poles of the magnetic material provided inside the developing roller. Thus, the developer is prevented from being discharged from the second discharge port at the normal time when the developer amount is not increasing. That is, the developer can be discharged from the second discharge port only when the developer increases.

  By providing the second discharge port at the end opposite to the first discharge port of the developer container, the developer is not discharged from the first discharge port by tilting the developing device, and the developer container Even if the developer amount increases, the developer is discharged from the second discharge port. Therefore, it is possible to prevent the developer amount in the developer container from increasing.

  Further, since the second discharge port is only provided at the end opposite to the first discharge port of the developer container, it is possible to prevent the developer amount in the developing device from increasing with a simple configuration.

1 is a schematic view of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an overall perspective view of a developing device provided in the image forming apparatus of FIG. 1. FIG. 3 is a cross-sectional view showing an appropriate amount of developer in the developing device of FIG. 2. FIG. 3 is a cross-sectional view showing a state in which the developer of the developing device of FIG. 2 is increased.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a trickle-type image forming apparatus 11 in which not only toner but also developer is replenished among electrophotographic systems using a two-component developer including toner and carrier. The image forming apparatus 11 includes an image forming unit 12, a transfer unit 13, an exposure unit 14, a paper feed unit 15, and a cleaning unit 16.

  The image forming units 12 are arranged at four locations along the intermediate transfer belt 18 of the transfer unit 13, and yellow (Y), magenta (M), cyan (C), and black (Bk) images from the cleaning unit 16 side, respectively. By performing the formation, a color image is formed on the surface of the intermediate transfer belt 18. Each image forming unit 12 includes a charging device 21, a developing device 22, and a cleaning device 23 around the photosensitive drum 20, as typically shown by the black image forming unit 12.

  The charging device 21 forms a predetermined surface potential on the surface of the photosensitive drum 20. This surface potential becomes an electrostatic latent image when exposed by the exposure unit 14.

  The developing device 22 supplies toner to the photosensitive drum 20. Above the developing device 22, a developer supply container 26 for supplying the developer to the developing device 22 is detachably installed.

  The cleaning device 23 collects the toner remaining on the surface after the transfer to the photosensitive drum 20 and cleans it.

  The transfer unit 13 bridges the intermediate transfer belt 18 between a pair of support rollers 27 and 28, drives the support roller 27 by a driving means (not shown), and drives the intermediate transfer belt 18 in the direction of arrow A. The transfer unit 13 is opposed to the primary transfer roller 31 that constitutes the primary transfer portion and the support roller 27 as opposed to the photoreceptor drum 20 as representatively shown by the black photoreceptor drum 20. And a secondary transfer roller 33 constituting a secondary transfer portion.

  The exposure unit 14 irradiates the photosensitive drum 20 with laser light, and forms an electrostatic latent image corresponding to image data read by a scanner (not shown).

  The sheet feeding unit 15 sequentially conveys the recording medium 36 accommodated in the sheet feeding cassette 35 to the secondary transfer unit via the conveyance roller 37. The toner image is transferred to the recording medium 36 conveyed to the secondary transfer portion, and the toner image transferred by the fixing unit 38 is fixed, and then is carried out to the discharge tray 39.

  The cleaning unit 16 can come into contact with and separate from the intermediate transfer belt 18, and collects and cleans toner remaining on the intermediate transfer belt 18 when approaching.

  FIG. 2 shows details of the developing device 22 according to the present invention. The developer container 41 constituting the developing device 22 has a rectangular shape in a top view extending along the photosensitive drum 20. Further, the interior is divided into two by a partition wall 42 along the longitudinal direction into a first housing portion 43 and a second housing portion 44.

  A developer supply port 46 formed on one end side of the first accommodating portion 43 and upstream of the developer moving direction communicates with the developer supply container 26. As a result, the developer is supplied from the developer supply container 26 to the developer storage container 41 through the developer supply port 46. In this embodiment, a two-component developer containing toner and carrier is used as the developer.

  As shown in FIG. 3, the first storage unit 43 stores a stirring screw 47 that transports the supplied developer to the end opposite to the developer supply port 46 while mixing and stirring.

  The second storage portion 44 stores a supply screw 48 and a developing roller 49 disposed so as to face the supply screw 48. The supply screw 48 supplies the toner to the developing roller 49 while conveying the developer in the opposite direction to the stirring screw 47. The developing roller 49 supplies toner to the photosensitive drum 20 and performs development.

  The first accommodating portion 43 and the second accommodating portion 44 are communicated with each other through communication ports 45 provided on both end sides of the partition wall 42. Thereby, the accommodated developer is circulated and moved between the first accommodating portion 43 and the second accommodating portion 44 by the agitating screw 47 and the supply screw 48.

  A first discharge port 51 for discharging the developer in the developer container 41 is provided at the end of the second storage unit 44 on the same side as the developer supply port 46.

  The developing roller 49 that receives the supply of toner from the supply screw 48 is disposed so as to be exposed from the opening 50 formed at a position facing the photosensitive drum 20 of the developer container 41 and close to the photosensitive drum 20. Has been. The developing roller 49 includes a magnet roller 52 inside, and a cylindrical sleeve roller 53 provided outside thereof so as to be rotatable independently of the magnet roller 52. The magnet roller 52 has five magnetic poles (N1, S1, N2, S2, N3) around it and is fixed.

  A developer regulating plate 56 is formed at the edge of the opening 50 of the developer container 41 so as to face the S1 pole among the five poles.

  Further, a second discharge port 58 is provided in the developer container 41 so as to face the S3 pole. Further, the second discharge port 58 is provided at an end portion on the opposite side of the first discharge port 51. The second outlet 58 is rectangular, has a width of 10 mm and a height of 2 mm.

  A discharge agent storage portion 59 is attached to the developer storage container 41 by welding, for example, so as to cover the second discharge port 58 around the second discharge port 58. The discharge agent storage portion 59 is a box-shaped storage container attached along the outer surface of the developer storage container 41.

  Next, the developing operation of the developing device 22 according to the present invention will be described.

  The developer conveyed to the second storage unit 44 by the stirring screw 47 and the supply screw 48 is lifted from the supply screw 48 onto the developing roller 49 by the magnetic force of the S2 pole. The developer lifted to the developing roller 49 is conveyed to the developer regulating plate 56 by the rotation of the developing roller 49 and the magnetic force of the N2 pole. In the developer regulating plate 56, the amount of developer sent to the developing roller 49 is regulated by a gap between the developer regulating plate 56 and the surface of the developing roller 49. In the present embodiment, the developer amount is regulated by adjusting the gap between the regulating plate 56 and the developing roller 49 to about 0.3 to 0.6 mm. However, in order to make the developer amount more stable, the developer regulation is performed. An S1 pole is provided at a portion facing the plate 56 to stabilize the developer regulating ability.

  The developer that has passed through the developer regulating plate 56 develops the latent image on the photosensitive drum 20 at the N1 pole. The developer that has been developed is returned into the developer container 41 through a gap 57 between the developer container 41 and the developing roller 49. The S3 pole that is the sealing electrode provided in the gap 57 prevents the developer from leaking out of the developer container 41 from the gap 57. Further, when the developer returned to the developer container 41 exceeds a predetermined developer amount, the developer climbs over a counter-wound screw (not shown) formed at the end of the supply screw 48 and passes through the first discharge port 51. Discharged.

  When the developing device 22 is tilted with the end on the first discharge port 51 side upward and the end on the second discharge port 58 side downward, for example, when the image forming apparatus 11 is installed in an inclined state, the first The amount of developer discharged from the discharge port 51 is reduced. Then, as shown in FIG. 4, the developer amount in the developing device 22 increases, and the increased developer is discharged from the second discharge port 58 and stored in the discharge agent storage portion 59. Thereby, it is possible to prevent the developer from increasing in the developing device 22 with a simple configuration. Further, by providing the discharge agent storage portion 59, it is possible to prevent the developer discharged from the second discharge port 58 from leaking into the image forming apparatus 11 and staining the inside of the image forming apparatus 11.

  Furthermore, by providing the second discharge port 58 at a position facing the sealing electrode S3, the developer is not discharged from the second discharge port 58 at the normal time when the developer amount is not increasing. Therefore, the developer can be discharged from the second discharge port 58 only when the developer increases.

  However, the developing device 22 according to the present invention is not limited to the above embodiment.

  The second discharge port 58 is not limited to the size and shape as long as the increased developer is appropriately discharged from the developing device 22. For example, the dimension may be 3 mm instead of 2 mm in height. Further, the shape may be a circle instead of a rectangle.

  The discharge agent storage portion 59 is not limited to the shape and the mounting method as long as the developer discharged from the second discharge port 58 is stored and does not interfere with other members in the image forming apparatus 11.

DESCRIPTION OF SYMBOLS 11 Image forming apparatus 22 Developing apparatus 41 Developer container 46 Supply port 47 Stirring screw 48 Supply screw 49 Developing roller 51 1st discharge port 58 2nd discharge port 59 Discharge agent storage part

Claims (2)

A developer containing container for containing the developer, a developing roller for carrying the developer in the developer containing container and adhering the toner to the photosensitive drum, and in the developer containing container while stirring the developer. A stirring screw for circulating the developer, a supply screw for supplying the developer circulated by the stirring screw to the developing roller, a replenishing port for replenishing the developer in the developer containing container, and a developer containing container In a developing device having a first discharge port provided at an end portion on the same side as the supply port, and discharging a circulating developer,
A second discharge port is provided at the end of the developer container opposite to the first discharge port,
The second discharge port is disposed opposite to a sealing pole that prevents leakage of the developer out of the developer container among the magnetic poles of the magnetic material provided inside the developing roller. A discharge agent storage section for storing the developer,
The developing device, wherein the discharge agent storage portion is attached to an outer surface of the developer storage container so as to cover the second discharge port . An image forming apparatus comprising the developing device according to claim 1 .

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