JP2010139924A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device configured to reliably discharge a desired amount of developer, and to provide an image forming apparatus. <P>SOLUTION: The developing device includes a developer container 11 in which the developer containing toner and carrier is stored. The developer container 11 is divided into a first storage part 16 and a second storage part 17 by a partitioning wall 15. The first storage part 16 and the second storage part 17 communicate with each other through communication parts 18 located on both end portions. The stored developer is stirred and circulatingly moved by a first conveying member 12 disposed in the first storage part 16 and a second conveying member 13 disposed in the second storage part 17. The developer container 11 includes: a discharge mechanism 20 capable of discharging the developer when the stored developer exceeds a reference amount; and a flow path cross-section area adjusting mechanism 21 located on the way of a developer circulation path, and on the upstream side of the discharge mechanism 20, for varying the flow path cross-section area. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device and an image forming apparatus.

  2. Description of the Related Art Conventionally, there is a so-called trickle type developing device in which a developer is supplied and discharged to prevent deterioration of a carrier contained in the developer.

  In such a trickle-type developing device, for example, a developer in which the amount of developer to be discharged is adjusted by opening and closing the discharge port of the developing tank with an open / close lid that reciprocally moves by a solenoid is known (for example, Patent Document 1).

JP-A-6-250517

  However, in the conventional developing device, even when the opening degree of the discharge port is the same, the amount of developer discharged greatly varies depending on the amount of developer in the developer container and the property of the developer. There is a problem of doing.

  Therefore, an object of the present invention is to provide a developing device and an image forming apparatus having a configuration capable of reliably discharging a desired amount of developer.

As a means for solving the above problems, the present invention provides:
A developer containing container for containing a developer including toner and a carrier, the developer containing container being separated into a first containing part and a second containing part by a partition wall; the first containing part and the second containing part; Are communicated with each other at the communicating portions on both ends, and the contained developer is stirred by the first conveying member disposed in the first accommodating portion and the second conveying member disposed in the second accommodating portion. A developing device that circulates while
The developer container includes a discharge mechanism that can be discharged when the amount of developer stored exceeds a reference amount, and a flow path cross-sectional area in the middle of the developer circulation path, upstream of the discharge mechanism. And a variable channel cross-sectional area adjusting mechanism.

  With this configuration, the flow path cross-sectional area adjustment mechanism can be driven and controlled, and the flow path cross-sectional area on the upstream side can be adjusted. Therefore, the developer discharge amount by the discharge mechanism can be freely adjusted. .

A deterioration degree detecting means for detecting a deterioration degree of the carrier;
It is preferable to further comprise control means for driving and controlling the flow path cross-sectional area adjusting means to adjust the flow cross-sectional area according to the degree of carrier deterioration detected by the deterioration degree detecting means.

  The deterioration degree detecting means, for example, has a configuration in which the degree of carrier deterioration is estimated according to the number of image formations in a state where the BW ratio is larger than the reference range or the BW ratio is smaller than the reference range. do it.

  With the above configuration, the flow passage cross-sectional area can be adjusted according to the degree of carrier deterioration, and the developer discharge amount can be adjusted. As a result, if the carrier is severely deteriorated, the flow path cross-sectional area can be reduced, the developer can be actively discharged, and the developer can be quickly replaced with a new one. On the other hand, if the carrier is hardly deteriorated, it is possible to increase the flow path cross-sectional area to reduce the developer discharge amount and to suppress wasteful consumption of the developer.

  The flow path cross-sectional area adjusting means is constituted by a part of a partition wall, and includes a partition plate that can rotate about the upstream side in the flow direction of the developer as a support shaft, and a drive unit that rotates the partition plate. What is necessary is just to be the structure.

The discharge mechanism includes a developer discharge port formed on the wall surface constituting the developer container so that the developer can be discharged when the liquid level of the developer reaches a predetermined value.
The developer discharge port is preferably arranged in a region corresponding to the tip rotation position of the partition plate.

  The flow path cross-sectional area adjusting means includes a coil portion disposed around an opening portion of the communication portion disposed in the vicinity of the upstream side of the discharge mechanism among the communication portions, an energization portion that energizes the coil portion, It is good also as a structure provided with.

  The flow path cross-sectional area adjusting means may include an open / close plate that opens and closes a communication portion disposed in the vicinity of the upstream side of the discharge mechanism, and a drive means that drives the open / close plate. Good.

  Further, according to the present invention, as means for solving the above-described problems, an image forming apparatus includes the developing device described above.

  According to the present invention, the flow passage cross-sectional area adjustment mechanism is provided on the upstream side of the discharge mechanism, and the flow passage cross-sectional area is changed. Therefore, the developer discharge amount can be freely adjusted, which is always optimal. It becomes possible to maintain the state.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. However, in the following description, the types, combinations, shapes, relative arrangements, and the like of the components are not intended to limit the technical scope of the present invention unless otherwise specified. In addition, terms indicating a specific direction or position (for example, “upper”, “lower”, “one end”, “other end”, etc.) are used as necessary, but use of these terms is referred to the drawings. However, the technical scope of the present invention is not limited by the meaning of the terms.

(1. Overall configuration)
FIG. 1 shows a so-called trickle-type image forming apparatus in which a developer including not only a toner but also a carrier or the like is replenished among electrophotographic systems using a two-component developer. The image forming apparatus generally includes an image forming unit 1, a transfer unit 2, an exposure unit 3, a paper feeding unit 4, a cleaning unit 5, a control unit 6, and the like.

  The image forming unit 1 is disposed at four locations along the intermediate transfer belt 29 of the transfer unit 2 and performs yellow (Y), magenta (M), cyan (C), and black (Bk) image formation from the left side, respectively. As a result, a color image is formed on the surface of the intermediate transfer belt 29. Each image forming unit 1 includes a charging device 8, a developing device 9, a cleaning device 10, and the like around the photosensitive drum 7.

  The charging device 8 forms a predetermined surface potential on the surface of the photosensitive drum 7. This surface potential becomes an electrostatic latent image when exposed by the exposure unit 3.

  As shown in FIGS. 2 and 3, the developing device 9 contains a stirring screw 12, a supply screw 13, and a developing roller 14 in a developer container 11. The detailed configuration of the developing device 9 will be described later.

  Above the developing device 9, as shown in FIG. 1, a developer replenishing container 27 for replenishing a replenishing two-component developer (hereinafter simply referred to as a developer) composed of toner and carrier is detachable. ing.

  The cleaning device 10 cleans the toner remaining on the surface after the transfer to the surface of the photosensitive drum 7.

  The transfer unit 2 spans an intermediate transfer belt 29 between a pair of support rollers 28, drives the support roller 28 by a driving means (not shown), and circulates the intermediate transfer belt 29 in an arrow direction. A transfer unit 30 and a secondary transfer unit 31 are provided.

  The exposure unit 3 irradiates the photosensitive drum 7 with laser light to form an electrostatic latent image corresponding to image data read by a scanner (not shown).

  The paper feed unit 4 sequentially conveys the recording medium 33 stored in the cassette 32 to the secondary transfer unit 31 via the conveyance roller 34. The toner image is transferred to the recording medium 33 conveyed to the secondary transfer unit 31, and the toner image transferred by the fixing unit 35 is fixed, and then is carried out to the discharge tray 36.

  The cleaning unit 5 can come in contact with and separate from the intermediate transfer belt 29, and can collect toner remaining on the intermediate transfer belt 29 by approaching the cleaning unit 5.

  The control unit 6 executes a developer replenishment process based on a detection voltage input from a magnetic permeability sensor (not shown) provided in the developer container 11 and changes the rotation position of the partition plate 21. Adjust the developer discharge amount.

(2. Development device)
Hereinafter, the configuration of the developing device 9 (the configuration in which the agitation screw 12, the supply screw 13, and the developing roller 14 are accommodated in the developer accommodating container 11) will be described in detail.

  That is, as shown in FIG. 3, the developer container 11 has a long box shape extending from one end side to the other end side, and the inside is separated from the first container 16 and the first container 16 along the longitudinal direction by the partition wall 15. It is divided into two housing parts 17. As shown in FIGS. 4 and 5, the partition wall 15 is formed with a base portion 15 b that gradually decreases in thickness from one side edge portion toward the other side edge portion, and a constant thickness on the distal end side thereof. Wall surface portion 15a. Both end sides of the first storage portion 16 and the second storage portion 17 are communicated with each other by communication portions 18a and 18b, and the stored developer is circulated while being stirred. The developer container 11 is disposed obliquely with respect to the first container 16 so that the second container 17 is positioned on the upper side.

  A developer replenishing port 19 is formed on one end side of the first accommodating portion 16, and the developer is replenished from the corresponding developer replenishing container 27. Here, a two-component developer containing toner and carrier is used as the developer. However, an external additive or the like may be further included in the developer.

  A developer discharge port 20 is formed on one end side of the second storage portion 17. The vertical position of the developer discharge port 20 is a position where the developer can be discharged when the liquid level of the developer in the developer container 11 exceeds the upper limit value of a reference range considered appropriate. As a result, the developer exceeding the reference range is appropriately discharged in the second storage portion 17 so that the deteriorated carrier does not remain in the developer storage container 11 for a long period of time. Further, the position of the developer discharge port 20 in the left-right direction may be an area corresponding to the tip position of the partition plate 21 described later. That is, among the partition plates 21, the tip position has the largest movement amount, and the developer becomes the highest by rotating to the upper position. Therefore, by providing the developer discharge port 20 at this position, the developer can It can be discharged effectively. Specifically, as shown in FIG. 7A, the developer discharge port 20 may be formed from the position corresponding to the tip position of the partition plate 21 toward the downstream side. However, since the direction of the developer is changed at the communication portion 18b, the developer is shifted from the position corresponding to the tip position of the partition plate 21 toward the upstream side as shown in FIG. 7B. It is preferable to form the agent discharge port 20. In particular, as shown in FIG. 7C, it is optimal that the center position of the opening is slightly shifted to the upstream side with respect to the position corresponding to the tip position of the partition plate 21.

  In one communication part 18b, as shown in FIGS. 3-6, a part of partition wall 15 is comprised with the partition plate 21 which can be rotated. The partition plate 21 has the same cross-sectional shape as the partition wall 15, and the mounting plate 22 is fixed with the wall surface of the developer container 11 interposed therebetween. A through hole 11 a and a long hole 11 b are formed in the wall surface of the developer container 11. The mounting plate 22 has protrusions 22a and 22b formed at two locations on both ends. The protrusions 22a and 22b are inserted through the through holes 11a and the long holes 11b, respectively, and are fitted and integrated with the partition plate 21, respectively. In this state, the partition plate 21 rotates around the projection 22a within a range where the projection 22b is regulated by the long hole 11b. A worm wheel 22c is integrated with the mounting plate 22, and a worm gear 23 is engaged therewith. The worm gear 23 is rotated by a stepping motor 24 to rotate the partition plate 21 forward and backward.

  As shown in FIG. 3, the stirring screw 12 is arranged in the first housing portion 16 with a configuration in which a spiral blade 12 b is provided around the rotating shaft 12 a. The agitation screw 12 is agitated while transporting the developer from the communication part 18b side to the communication part 18a side by being driven to rotate.

  As shown in FIG. 3, the supply screw 13 is arranged in the second housing portion 17 with a configuration in which a spiral blade 13 b is provided around the rotation shaft 13 a, similarly to the stirring screw 12. The supply screw 13 is driven to rotate, thereby transferring the developer from the communication portion 18 a side to the communication portion 18 b side and supplying the developer to the developing roller 14.

  As shown in FIG. 2, the developing roller 14 includes a plurality of permanent magnets 26 accommodated in a cylindrical sleeve 25 (here, five permanent magnets S2, N2, S1, N1, and S3 are connected to the developing roller 14). In order and clockwise.) The sleeve 25 is configured to rotate in the direction of the arrow in the drawing by a sleeve driving means (not shown).

(3. Operation)
Next, the operation of the image forming apparatus having the above configuration will be described.

  At the time of image formation, color print data obtained by reading an image or image data output from a personal computer or the like is subjected to predetermined signal processing, and then yellow (Y), magenta (M), cyan (C ) And black (Bk) image signals of each color are transmitted to each image forming unit 1.

  In each image forming unit 1, a laser beam modulated by an image signal is projected onto each photosensitive drum 7 to form an image latent image. Then, toner is supplied from the developing device 9 to the photosensitive drum 7.

  In the developing device 9, the developer stored in the developer container 11 is circulated while being stirred by rotationally driving the stirring screw 12 and the supply screw 13. Then, toner is supplied from the supply screw 13 to the developing roller 14, scraped off by the regulating member 11 a to a constant amount, and then conveyed to the photosensitive drum 7.

  As a result, yellow, magenta, cyan, and black toner images are formed on the respective photosensitive drums 7. The formed yellow, magenta, cyan, and black toner images are sequentially primary-transferred on the moving intermediate transfer belt 29 by the primary transfer unit 30. The superimposed toner image formed on the intermediate transfer belt 29 in this way moves to the secondary transfer unit 31 as the intermediate transfer belt 29 moves.

  A recording medium 33 is supplied from the paper feeding unit 4. The supplied recording medium 33 is conveyed between the secondary transfer unit 31 and the intermediate transfer belt 29 by the conveyance roller 34, and the toner image formed on the intermediate transfer belt 29 is transferred. The recording medium 33 to which the toner image has been transferred is further conveyed to the fixing unit 35, where the transferred toner image is fixed and then discharged to the discharge tray 36.

  By the way, in the developing device 9, a printed part (toner) in a BW ratio (output image (here, 100% printing that forms only an image portion on paper means a so-called “solid patch”)). If a large amount of images with a low ratio) is printed, the toner consumption is reduced and a new developer is not replenished. For this reason, the carrier contained in the developer in the developer container 11 is circulated while being stirred for a long time, and the ability to charge the toner (charging ability) is deteriorated.

  Therefore, the stepping motor 24 is driven to rotate the partition plate 21 from the reference position (the same plane as the partition wall 15) to the upper position on the second housing portion 17 side, so that the flow path cross-sectional area of the second housing portion 17 is reached. Is made to forcibly raise the liquid level of the flowing developer. As a result, the developer in the developer container 11 is easily discharged through the developer discharge port 20.

  Further, in the developing device 9, when a large amount of images with a high BW ratio is printed, the toner consumption increases, and the carrier has sufficient charging ability, but the developer discharge port 20 is used. Will be discharged. Therefore, the stepping motor 24 is driven to rotate the partition plate 21 from the reference position to the lower position on the first housing portion 16 side. As a result, the liquid level of the developer flowing in the second storage portion 17 is temporarily lowered, and the developer is hardly discharged from the developer discharge port 20.

  Normally, the partition plate 21 does not stay at any one of the upper position, the reference position, or the lower position for a long period of time. Therefore, when the rotation position is switched to any position, the deteriorated carrier is long. Problems such as staying for a period or discharging undegraded carriers are eliminated. For example, when the partition plate 21 is switched from the lower position or the reference position to the upper position, a large amount of developer (deteriorated carrier) is discharged from the developer discharge port 20 in the short term. When the upper position is switched to the reference position or the lower position, the discharge amount is suppressed and new developer (carrier) is stored. Thereby, a sufficient amount of carriers having a desired charging ability can be obtained.

(4. Other embodiments)
In addition, this invention is not limited to the structure described in the said embodiment, A various change is possible.

  For example, to drive the partition plate 21 of the developer container 11, power from the stepping motor 24 is transmitted via the worm gear 23 and the worm wheel. However, a cam or a solenoid can be used. When a cam is used, the partition plate 21 is biased in one direction of rotation about the protrusion 22a, and the eccentric cam is brought into contact with the partition plate 21 or a member integrated therewith. Good. According to this, the rotational position of the partition plate 21 can be accurately set by rotating the cam and changing the contact position. Moreover, when utilizing a solenoid, the rod provided so that advance / retreat is possible is connected with the partition plate 21 or the member integrated with this. Then, by exciting and demagnetizing the solenoid, the protruding position of the rod can be changed and the position where the partition plate 21 is rotated can be adjusted.

  Further, the partition plate 21 provided on the partition wall 15 of the developer container 11 is not limited to one side of the communication portion 18b, and may be provided on both sides as shown in FIG. That is, the partition plate 21 may be formed on the upstream side with the communication portion 18b interposed therebetween, and the partition plate 41 may be formed on the downstream side. In this case, the position of the developer discharge port 20 is the end of the second accommodating portion 17, and a blade 13 c that is wound reversely to the blade 13 b is formed at the end of the supply screw 13 (on the developer discharge port 20 side). . However, unlike the partition plate 21, the partition plate 41 cannot be rotated. According to this configuration, when the partition plate 21 is located at the reference position or the lower position, the flow resistance by the reversely wound blades 13c and the function of the partition plate 41 projecting obliquely upward with respect to the developer flow direction. Thus, the developer is not easily discharged from the developer discharge port 20. On the contrary, when the partition plate 21 is located at the upper position, the liquid level of the developer becomes high and the developer easily gets over the reversely wound blades 13c.

  Further, instead of forming the partition plate 21 on the partition wall 15 of the developer container 11, an openable / closable shutter can be provided. That is, as shown in FIG. 9, a shutter (opening / closing plate) 38 having an opening 39 that is substantially the same as the one communication portion 18 is provided so as to be slidable along the partition wall 15 and communicated by changing the slide position. What is necessary is just to make it change the opening degree of the part 18. FIG.

  Further, instead of forming the partition plate 21 on the partition wall 15 of the developer container 11, as shown in FIG. 10, a plurality of wire rods 42 made of a magnetic material such as iron are arranged in parallel in the communication portion 18b. You may make it provide the conducting wire 43 in the coil shape around this. As a result, when a direct current is supplied to the conducting wire 43, the wire 42, which is a magnetic material, is magnetized by the electromagnetic induction action, and the carrier passing through the communication portion 18b can be captured around the wire 42. As a result, the opening area of the communication portion 18b is reduced, and the developer is difficult to pass. That is, the developer is likely to stay on the upstream side of the communication portion 18b, the liquid level rises, and a state where the developer is easily discharged from the developer discharge port 20 can be obtained.

  Further, in the above-described embodiment, the method for adjusting the flow path cross-sectional area when a large amount of printing is performed when the BW ratio is large or conversely small is described. The flow path cross-sectional area is adjusted even when the developer in the container 11 is biased or when the system speed (rotational speed of the photosensitive drum 7, paper transport speed, etc.) is changed by printing on cardboard. You may make it do. For example, when the image forming apparatus is installed at an inclination, if the discharge mechanism side is high, the flow path cross-sectional area may be reduced to facilitate the discharge of the developer, and conversely if the discharge mechanism side is low, the flow path The cross-sectional area may be increased to make it difficult for the developer to be discharged.

  In addition, as described above, various modifications of the component parts have been described, but the changeable parts are not limited to these, and depending on the configuration of the image forming apparatus and other parts to be used, as appropriate. It is possible to change. For example, although the cylindrical photosensitive drum 7 is used as the photosensitive member, the present invention is not limited to such a form, and an endless belt type photosensitive member can be used instead. In addition, although the charging device 8 has a cylindrical shape, other forms (for example, a rotary type or a fixed type brush type, a wire discharge type) can be used instead. Further, the image forming apparatus may be any one of a copying machine, a printer, a facsimile machine, and a multifunction machine having these functions in combination.

1 is a schematic front sectional view of an image forming apparatus according to an embodiment. FIG. 2 is a schematic front sectional view of the developing device in FIG. 1. FIG. 3 is a cross-sectional view of the developer storage container of FIG. 2 taken along line AA. It is a disassembled perspective view of the partition wall and partition plate of FIG. It is a perspective view of the partition wall and partition plate of FIG. FIG. 3 is a cross-sectional view of the developer container shown in FIG. 2 at a partition plate. FIG. 4 is a schematic explanatory diagram illustrating a positional relationship of a developer discharge port with respect to the partition plate of FIG. 3. It is a schematic sectional drawing of the image development apparatus concerning other embodiment. It is a general | schematic partial expansion perspective view of the partition wall which concerns on other embodiment. It is a general | schematic partial expansion perspective view of the communication part which concerns on other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming unit 2 ... Transfer unit 3 ... Exposure unit 4 ... Paper feed unit 5 ... Cleaning unit 6 ... Control unit 7 ... Photoconductor drum 8 ... Charging device 9 ... Developing device 10 ... Cleaning device 11 ... Developer container 12 ... Agitating screw (first conveying member)
12a ... Rotating shaft 12b ... Blade 13 ... Supply screw (second conveying member)
DESCRIPTION OF SYMBOLS 13a ... Rotating shaft 13b, 13c ... Blade | wing 14 ... Developing roller 15 ... Partition wall 16 ... 1st accommodating part 17 ... 2nd accommodating part 18a, 18b ... Communication part 19 ... Developer supply port 20 ... Developer discharge port (discharge mechanism) )
21 ... Partition plate (channel cross-sectional area adjustment mechanism)
DESCRIPTION OF SYMBOLS 22 ... Mounting plate 23 ... Worm gear 24 ... Stepping motor 25 ... Sleeve 26 ... Permanent magnet 27 ... Developer supply container 28 ... Support roller 29 ... Intermediate transfer belt 30 ... Primary transfer part 31 ... Secondary transfer part 32 ... Cassette 33 ... Recording medium 34 ... Conveying roller 35 ... Fixing unit 36 ... Discharge tray 37 ... Inner wall 38 ... Shutter (opening / closing plate)
39 ... Opening 41 ... Partition plate 42 ... Wire 43 ... Conductor

Claims (7)

A developer containing container for containing a developer including toner and a carrier, the developer containing container being separated into a first containing part and a second containing part by a partition wall; the first containing part and the second containing part; Are communicated with each other at the communicating portions on both ends, and the contained developer is stirred by the first conveying member disposed in the first accommodating portion and the second conveying member disposed in the second accommodating portion. A developing device that circulates while
The developer container includes a discharge mechanism that can be discharged when the amount of developer stored exceeds a reference amount, and a flow path cross-sectional area in the middle of the developer circulation path, upstream of the discharge mechanism. A developing device comprising: a variable flow passage area adjusting mechanism. A deterioration degree detecting means for detecting a deterioration degree of the carrier;
The apparatus further comprises control means for adjusting the flow path cross-sectional area by drivingly controlling the flow path cross-sectional area adjusting means according to the degree of carrier deterioration detected by the deterioration degree detecting means. Item 2. The developing device according to Item 1.   The flow path cross-sectional area adjusting means is constituted by a part of a partition wall, and includes a partition plate that can rotate about the upstream side in the flow direction of the developer as a support shaft, and a drive unit that rotates the partition plate. The developing device according to claim 1, wherein The discharge mechanism includes a developer discharge port formed on the wall surface constituting the developer container so that the developer can be discharged when the liquid level of the developer reaches a predetermined value.
The developing device according to claim 3, wherein the developer discharge port is disposed in a region corresponding to a tip rotation position of the partition plate.   The flow path cross-sectional area adjusting means includes a coil portion disposed around an opening portion of the communication portion disposed in the vicinity of the upstream side of the discharge mechanism among the communication portions, an energization portion that energizes the coil portion, The developing device according to claim 1, further comprising:   The flow path cross-sectional area adjusting means includes an open / close plate that opens and closes a communication portion arranged in the vicinity of the upstream side of the discharge mechanism among the communication portions, and a drive means that drives the open / close plate. The developing device according to claim 1 or 2.   An image forming apparatus comprising the developing device according to claim 1.