JP2008185862A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable to enlarge volume capacity of a space around a conveying member in accordance with a toner amount, and to prevent breakage of the conveying member caused by toner aggregation around the conveying member, and to provide an image forming apparatus. <P>SOLUTION: The developing device includes: a spiral 32 as the conveying member rotatably disposed in the toner conveying space 33 that extends in the width direction of a transfer sheet, for conveying the toner T supplied from one end side thereof to the other end side thereof, while agitating the toner T; a toner retreat space 34 adjacent to the toner conveying space 33; and a partitioning wall 35 disposed between the toner conveying space 33 and the toner retreat space 34, configured to allow the toner to be conveyed in the toner conveying space 33 in a normal state, but when the toner conveying space 33 is filled with the toner T, to enlarge the toner conveying space 33 by the use of the toner retreat space 34. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device provided in an image forming apparatus such as a copying machine, a printer, and a facsimile that employs an electrophotographic system, and a multifunction machine that includes these functionally, and an image forming apparatus that includes the developing device.

  Conventionally, with regard to toner transport for supplying toner stored in a toner storage space to a photoconductor, toner transport using a spiral disposed in a toner supply path from the toner storage space to the photoconductor as a transport member is generally used. Has been adopted.

  This spiral enters the spiral from the toner storage space (hereinafter referred to as “spiral upstream side”) and the toner amount exits from the spiral to the photosensitive member (hereinafter referred to as “spiral downstream side”). However, the amount of toner around the spiral often changes due to temporary clogging on the downstream side of the spiral or temporary increase in toner on the upstream side of the spiral.

  In this case, there is a case in which the toner is aggregated around the spiral due to the stress generated around the spiral, and the spiral is damaged due to the aggregation.

  For this reason, as the amount of toner stored in the toner storage space changes, the movable wall constituting a part of the toner storage space and the movable wall provided in the toner storage space are displaced to reduce the volume in the toner storage space. The technique to do is known (for example, refer patent documents 1 and 2).

  10 and 11 show an example of such a conventional developing device (see Patent Document 1). FIG. 10 is a cross-sectional view of the main part of the movable container in a normal state in a toner container as a conventional developing device. FIG. 6 is a cross-sectional view of a main part in a movable wall displacement state in a toner container as a conventional developing device.

  10 and 11, the toner container 70 is rotatably held in the container main body 72 so as to agitate the toner T in the toner storage space 71 and a container main body 72 that forms a toner storage space 71 in which the toner T is stored. The agitating blade 73, a movable wall 74 that is rotatably supported by the container main body 72 and constitutes a part of the toner storage space 71, and urges the movable wall 74 from the outer wall surface side to the toner storage space 71 side. A spring 75 that is rotatably supported by the container main body 72, a transport roller 76 that supplies toner T stored in the toner storage space 71 to a photoconductor (not shown), and toner supply by the transport roller 76. A regulating plate 77 for regulating the amount and frictionally charging the toner T is provided.

The movable wall 74 is at a retracted position so that the volume of the toner storage space 71 is increased as shown in FIG. 10 when the amount of toner T stored in the toner storage space 71 is large. When the toner amount of the toner T stored in 71 is small, the toner storage space 71 is displaced so that the volume of the toner storage space 71 is reduced by the urging of the spring 75 as shown in FIG.
JP 05-216343 A Japanese Patent Application Laid-Open No. 07-281521

  However, the developing device (toner container) configured as described above is intended to use up the toner in the toner container without waste. Therefore, the toner storage space 71 is reduced according to the decrease in the toner amount accompanying the supply of the toner T. The volume of the toner is reduced, and toner aggregation around the spiral is caused by a change in the toner amount around the spiral due to temporary clogging on the downstream side of the spiral or temporary increase of toner on the upstream side of the spiral. The problem that the resulting spiral breakage cannot be prevented has occurred.

  Therefore, in consideration of the above circumstances, the present invention can expand the volume of the space around the conveying member in accordance with the amount of toner, and thus can prevent the conveying member from being damaged due to toner aggregation around the conveying member. An object of the present invention is to provide a developing device that can be used.

  The developing device and the image forming apparatus of the present invention are rotatably disposed in a toner conveyance space extending in the transfer paper width direction, and convey the toner supplied from one end side while stirring to the other end side, It is provided between a toner evacuation space adjacent to the toner conveyance space, and between the toner conveyance space and the toner evacuation space, and always allows toner conveyance in the toner conveyance space and toner is contained in the toner conveyance space. And a partition wall that expands the toner conveyance space by using the toner evacuation space when the toner is filled.

  At this time, it is preferable that the partition wall be deformed or displaced toward the toner retracting space when the toner conveying space is filled with toner.

  Further, it is preferable that the toner evacuation space is formed on a side opposite to a swelled side of the toner accompanying a toner conveyance action in a cross-sectional direction generated by the rotation direction of the conveyance member and the bottom surface of the toner evacuation space.

  Furthermore, the present invention can be an image forming apparatus employing the developing device and the image forming apparatus having any of the above-described configurations.

  The developing device of the present invention can expand the volume of the spiral peripheral space according to the amount of toner, and thus can prevent the conveyance member from being damaged due to toner aggregation around the conveyance member.

  Next, the present invention will be described with reference to the drawings, which is applied to a developing device and an MFP as an image forming apparatus according to an embodiment of the present invention.

  FIG. 1 is an explanatory diagram of a multifunction peripheral as an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view of peripheral devices of a developing device according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a cross-sectional view of the main part of the developing device of the present invention in the normal state of the toner volume, and FIG. 5 is a cross-sectional view of the main part of the developing device of the present invention in the expanded state of the toner volume.

(Overall configuration of MFP)
As shown in FIG. 1, a multi-function machine 1 as an image forming apparatus according to an embodiment of the present invention includes a plurality of transfer paper storage apparatuses 3, 4, 5 that can be pulled out from the front surface of an apparatus body 2, and the transfer apparatus. In order to make it possible to use transfer paper different from the paper storage devices 3, 4, and 5, a manual feed tray 6 provided on one side of the apparatus body 2 so as to be openable and closable, and various types of copiers, facsimiles, and scanners An automatic document feeder (ADF) 7 used when reading a document as a function, and an operation unit 9 having a display screen 8 and performing setting / selection operations of various functions and the like are provided.

  Note that the shape, configuration, function, and the like of the multifunction machine 1 are not limited to those shown in the drawings. Further, for example, it does not hinder the installation of optional equipment such as a sorter.

(Internal structure of MFP)
Further, the apparatus main body 2 takes out the transfer paper (not shown) stored in the transfer paper storage devices 3, 4, 5 or the manual feed tray 6 into the apparatus main body 2 and is disposed on the other side surface of the apparatus main body 2. A transport path 11 that transports the paper toward the paper tray 10, a registration sensor 12 that is disposed upstream of the transport path 11 in the transfer paper transport direction and detects the transfer paper, and a transfer paper transport direction in the transport path 11 relative to the resist sensor 12 The pair of registration rollers 13 disposed on the downstream side, the image forming unit 14 disposed on the downstream side of the conveyance path 11 in the transfer sheet conveyance direction with respect to the registration sensor 12, and the image forming unit 14 are transferred to the surface of the transfer sheet. The fixing unit 15 for fixing the toner image on the surface of the transfer paper, the branch path 16 disposed on the downstream side of the transport path 11 in the transfer paper transport direction from the fixing section 15, and the transfer paper guided to the branch path 16 are switched. After a single-sided printing process when there are a plurality of originals set on the ADF 7 and a reverse path 18 that returns to the transport path 11 upstream of the registration sensor 12 in the transfer paper transport direction with the front and back reversed via the back path 17. And a reverse discharge path 19 for discharging the transfer sheet to the discharge tray 10 in a state where the discharge surface of the transfer sheet is aligned with the document order.

  The registration sensor 12 detects the transfer paper and synchronizes the position of the leading edge of the transfer paper with the position of the toner image formed on the surface of the photosensitive drum 20, and the registration sensor 12 detects the leading edge of the transfer paper. Then, the rotation driving of the registration roller pair 13 is started after a lapse of a predetermined time, and the rotation driving of the registration roller pair 13 is stopped after the lapse of a predetermined time after the registration sensor 12 detects the trailing edge of the transfer paper.

  The registration roller pair 13 is connected to a drive source (not shown) such as a motor. Then, in a stationary state, the registration roller pair 13 instantaneously stops the transfer paper when the front end of the transfer paper is nipped, and corrects the oblique feeding of the transfer paper by bending the transfer paper. .

  The image forming unit 14 includes a photosensitive drum 20, a charging device 21, an exposure device 22, a developing device (developing apparatus) 23, a transfer device 24, a cleaning device 25, and a static eliminating device 26 arranged around the photosensitive drum 20. I have.

  As a result, in the image forming unit 14, the photosensitive drum 20 is rotationally driven at a predetermined process speed (circumferential speed) by a driving unit (not shown), and the surface thereof is uniformly charged to a predetermined polarity and potential by the charging device 21. .

  An electrostatic latent image is formed on the surface of the charged photosensitive drum 20 by the exposure device 22. Here, for example, the exposure device 22 is connected via a communication line such as a print data read by a scanner unit using the ADF 7 by a copying machine function, a print data received through a telephone line by a facsimile function, or a network by a printer function. Based on the print data output from a personal computer or the like, the surface of the photoconductive drum 20 is irradiated with laser light, and the charge on the laser light irradiated portion on the surface of the photoconductive drum 20 is removed. An electrostatic latent image is formed.

  The electrostatic latent image formed on the surface of the photosensitive drum 20 is developed as a toner image by electrostatically attaching a charged toner by the developing device 23. Further, the toner image is transferred onto the transfer paper as a transfer image by the transfer device 24.

  At this time, the photosensitive drum 20 having the toner image transferred onto the transfer paper is removed by the cleaning device 25 and the charge is removed by the charge removal device 26 for charging at the next image formation.

(Configuration of developing device 23)
As shown in FIG. 2, the developing device 23 supplies toner stored in a toner container (toner storage space) 27 detachable (replaceable) to the multifunction machine main body 2 to the photosensitive drum 20. A spiral unit 30 connected to the container 27 in a toner supply state, and a stirring unit 40 for supplying the toner conveyed by the spiral unit 30 in the transfer paper width direction (see arrow A in FIG. 2) to the photosensitive drum 20 are provided. Yes.

  The spiral unit 30 feeds the toner supplied from the toner container 27 in the width direction of the transfer paper while stirring, and then supplies the toner to the stirring unit 40. The toner supply port is provided on the bottom surface near the end opposite to the toner container 27. A hollow spiral container body 31 formed in the width direction of the transfer paper (not shown) formed therein, a toner conveyance space 33 formed in the spiral container body 31 so that the spiral 32 as a conveyance member is positioned, and a toner conveyance space 33 A toner evacuation space 34 formed in the spiral container main body 31 and a deformable partition wall 35 for partitioning the toner conveyance space 33 and the toner evacuation space 34.

  The agitating unit 40 supplies toner to the photosensitive drum 20 while circulating and moving the toner therein, and supports the spiral unit 30 on the upper surface and faces a toner supply port formed in the spiral unit 30. A lid body 41 (not shown), a stirring container body 42 whose upper surface open end is closed to the lid body 41, and a stirring container body in order from the upstream side of the stirring path from the toner supply hole to the photosensitive drum 20 42, a pair of spiral feeders (stirring mixers) 43 and 44 rotatably supported by 42, a developing roller 45 facing the photosensitive drum 20, and a toner supply amount by the developing roller 45 is regulated and the toner is frictionally charged. The amount of toner in the stirring container main body 42 is detected by being provided on the outer wall surface in the vicinity of the restriction plate 46 and the toner supply hole of the stirring container main body 42. And a toner sensor 47 that.

  In addition, a partition wall 42 a that isolates the spiral feeders 43 and 44 is formed inside the stirring vessel main body 42. At both ends of the partition wall 42a, a gap (both not shown) is formed between the vertical wall of the stirring unit 40 and one of the stirring units 40 (by a spiral feeder 43 provided below the toner supply hole ( For example, after the toner is agitated and conveyed (forward direction) in FIG. 3, the toner is folded back in the gap on one side and the other of the agitation unit 40 by the spiral feeder 44 (for example, the front side in FIG. 3). A circulation path is formed in which the toner is agitated and conveyed (return path) to the other side and is turned back again in the gap on the other side.

  In the present embodiment, the spiral feeder 43 is formed with a clockwise spiral in order to supply the toner along the axial direction by rotating in the counterclockwise direction shown in the drawing. Further, the spiral feeder 44 is formed in a counterclockwise spiral in order to supply toner along the axial direction by rotating in the counterclockwise direction shown in the figure.

  Therefore, when the spiral feeder 43 is rotated in the counterclockwise direction, the toner is conveyed in the depth direction of the paper surface of FIG. 3, whereas when the spiral feeder 44 is rotated in the counterclockwise direction, the toner is conveyed in the forward direction of the paper surface. become. Thus, the toner is circulated and conveyed through the gaps at both ends of the partition wall 42 a so as to wrap around the inside of the stirring unit 40, and the toner conveyed by the spiral feeder 44 is supplied to the developing roller 45. The spiral feeders 43 and 44 can reverse the toner circulation direction by reversing the rotation direction thereof.

  The developing roller 45 is disposed so that the peripheral surface thereof faces the peripheral surface of the photosensitive drum 20. Therefore, the toner being conveyed to the developing roller 45 is supplied to the peripheral surface of the photosensitive drum 20 via the developing roller 45, and thereby a toner image is formed on the peripheral surface of the photosensitive drum 20.

  The rotation axis of the spiral 32 and the rotation axis of the spiral feeder 43 are arranged so as to be parallel with the toner supply port and the toner supply hole described above interposed therebetween.

  The toner sensor 47 is disposed in the vicinity of the toner supply hole, and the amount of toner in the vicinity of the toner supply hole is detected by the control circuit of the exposure device 22 based on the output signal.

  In the above configuration, as shown in FIG. 4, when toner T (only shown in FIGS. 4 and 5) is supplied from the toner container 27 to the spiral unit 30, the toner T is transported as the spiral 32 rotates. While being agitated in the space 33, it is guided to the bottom surface of the spiral container body 31, and from the toner supply port 31 a (only shown in FIGS. 4 and 5) opposite to the toner container 27 to the agitating container body 42 via the toner supply hole. And toner T are supplied.

  At this time, the toner conveyance space 33 also functions as a temporary retreat place for the replenishment toner in the toner supply path from the toner container 27 to the photosensitive drum 20, and when the toner T in the toner conveyance space 33 is small, the toner T is transported so that the illustrated left wall (downstream in the toner transport direction in the cross-sectional direction) of the toner transport space 33 is raised by the rotation direction of the spiral 32 (cross-sectional reference in FIG. 4: clockwise direction).

  Therefore, the above-described toner evacuation space 34 is on the right side (in the cross-sectional direction) opposite to the rising side of the toner T due to the toner conveying action in the cross-sectional direction generated by the rotation direction of the spiral 32 and the bottom surface of the spiral container body 31. By forming on the upstream side in the toner conveyance direction, the right wall in the figure of the toner conveyance space 33 is normally formed by the partition wall 35.

  As a result, it is possible to make the partition wall 35 difficult to receive the rising load of the toner T generated by the rotation of the spiral 32, and the partition wall 35 is unexpectedly deformed by the rising load, so that the volume of the toner evacuation space 34 is increased. It prevents it from expanding.

  Then, when the toner T in the toner transport space 33 temporarily increases due to some influence such as the toner T supplied from the toner container 27 is not supplied to the stirring unit 40, as shown in FIG. The partition wall 35 is deformed (displaced) toward the toner evacuation space 34 before the toner T is filled in the transport space 33, and the volume of the toner transport space 33 is substantially enlarged.

  Therefore, the toner T is filled in the toner conveyance space 33 and the toner T is solidified, so that it is possible to suppress the generation of stress and the aggregation of the toner that eventually cause the spiral 32 to be damaged.

  Note that the partition wall 35 is less likely to cause adhesion of the toner T if it is a member (thickness 0.1 mm to 0.2 mm) such as a PET film, and can have appropriate elasticity (strength). In particular, it is not limited to these.

(Modification 1)
In the above embodiment, the partition wall 35 of the spiral unit 30 is formed in a deformable film shape. However, for example, as shown in FIGS. 6 and 7, a spiral unit 50 having a displaceable partition wall 55 may be used. .

  6 and 7, the spiral unit 50 has a hollow spiral container body 51 extending in the transfer paper width direction in which a toner supply port 51a is formed on the bottom surface near the end opposite to the toner container 27, and a spiral 52. As described above, the toner conveyance space 53 formed in the spiral container body 51, the toner evacuation space 54 formed in the spiral container body 51 adjacent to the toner conveyance space 53, the toner conveyance space 53, and the toner evacuation space 54. And a partition wall 55 for partitioning.

  The partition wall 55 is configured such that the peripheral wall thereof is in close contact with the inner wall surface of the toner retracting space 54. In the first modification, the partition wall 55 has a protrusion 56 formed on the peripheral wall in the vertical direction and engages with a guide groove 57 formed in the toner retracting space 54, thereby causing the partition wall 55 to move in the depth direction of the toner retracting space 54 (illustrated). As shown in FIG. 6, the right wall of the toner conveyance space 53 is normally formed by a partition wall 55 by urging of a spring 58 as shown in FIG.

  Then, when the toner T in the toner transport space 53 temporarily increases due to some influence such as the toner T supplied from the toner container 27 is not supplied to the stirring unit 40, as shown in FIG. When the toner T is filled in the transport space 53, the partition wall 55 is displaced to the back side (right side in the drawing) of the toner transport space 53 against the bias of the spring 58, and the volume of the toner transport space 53 is substantially reduced. To enlarge.

  Therefore, the toner T is filled in the toner conveyance space 53 and the toner T is solidified, and finally, the generation of stress that causes damage to the spiral 52 and toner aggregation can be suppressed.

(Modification 2)
In the above embodiment, the partition wall 35 of the spiral unit 30 is formed in a deformable film shape. However, for example, as shown in FIGS. 8 and 9, a spiral unit 60 including a deformable partition wall 65 may be used. .

  8 and 9, the spiral unit 60 has a hollow spiral container body 61 extending in the transfer paper width direction in which a toner supply port 61a is formed on the bottom surface near the end opposite to the toner container 27, and a spiral 62. As described above, the toner conveyance space 63 formed in the spiral container body 61, the toner evacuation space 64 formed in the spiral container body 61 adjacent to the toner conveyance space 63, the toner conveyance space 63, and the toner evacuation space 64 are provided. And a partition wall 65 for partitioning.

  As the partition wall 65, a film-like material made of an elastically deformable material is used, and its peripheral portion is fixed to the inner wall surface of the toner-reserving space 64. Therefore, as shown in FIG. An illustrated right wall of the transfer space 63 is formed.

  Then, when the toner T in the toner transport space 63 temporarily increases for some reason, such as when the toner T supplied from the toner container 27 is not supplied to the stirring unit 40, as shown in FIG. When the toner T is filled in the conveyance space 63, the partition wall 65 is deformed to the back side (right side in the drawing) so as to expand, and the volume of the toner conveyance space 63 is substantially enlarged.

  Therefore, the toner T is filled in the toner conveyance space 63 and the toner T is agglomerated, and finally, the generation of stress that causes damage to the spiral 62 and toner aggregation can be suppressed.

  As described above, in the developing device of the present invention, the partition wall 35 (55, 65) always has a suitable volume in the toner conveyance space 33 (53, 63).

  Therefore, for example, if the partition wall 35 (55, 65) is eliminated and the volume of the toner transport space 33 (53, 63) is simply increased, the toner transport space 33 (53, 53) in the normal state (see FIG. 4) is used. 63), the amount of toner T with respect to the volume of 63) becomes small, and it becomes difficult to efficiently convey the toner, and toner waste and excessive toner are generated.

  However, like the partition wall 35 (55, 65) in the developing device of the present invention, the toner transport space 33 (53, 63) is always a suitable volume, and the toner transport space 33 is (53, 63) toner T. When it is satisfied, the toner conveyance space 33 (53, 63) is substantially enlarged, so that it is possible to improve the efficiency of toner conveyance and to prevent the generation of waste toner and excess toner.

  In the above embodiment, the developing device of the present invention is applied to a multifunction machine as an image forming apparatus. However, a copying machine, a printer, a facsimile using an electrophotographic system using toner, and these are functionally used. Needless to say, the present invention can be applied to all image forming apparatuses such as multifunction peripherals provided in the above.

1 is an explanatory diagram of a multifunction peripheral as an image forming apparatus according to an embodiment of the present disclosure. 1 is a perspective view of a developing device peripheral device according to an embodiment of the present invention. 1 is a cross-sectional view of a developing device according to an embodiment of the present invention. FIG. 4 is a cross-sectional view of a main part in a toner volume normal state in the developing device of the present invention. FIG. 4 is a cross-sectional view of a main part in a toner volume enlarged state in the developing device of the present invention. FIG. 10 is a cross-sectional view of a main part of a first modification of a toner volume normal state in the developing device of the present invention. FIG. 10 is a cross-sectional view of a main part of a first modified example of a toner volume expansion state in the developing device of the present invention. FIG. 10 is a cross-sectional view of a main part of a second modified example of a toner volume normal state in the developing device of the present invention. FIG. 10 is a cross-sectional view of a main part of Modification 2 of the developing device of the present invention in a toner volume enlarged state. It is sectional drawing of the principal part of the movable wall normal state in the toner container as the conventional developing device. FIG. 10 is a cross-sectional view of a main part in a movable wall displacement state in a toner container as a conventional developing device.

Explanation of symbols

1 ... Multifunction machine (image forming device)
23. Developing device (developing device)
30 ... Spiral unit 32 ... Spiral (conveying member)
33 ... Toner transport space 34 ... Toner escape space 35 ... Partition wall

Claims (4)

  A transport member that is rotatably disposed in the toner transport space and transports the toner supplied from one end side to the other end side while stirring, a toner evacuation space adjacent to the toner transport space, and the toner transport space; Provided between the toner evacuation space and normally allows toner conveyance in the toner conveyance space, and when the toner conveyance space is filled with toner, the toner evacuation space is used to convey the toner. A developing device comprising: a partition wall that expands the space.   The developing device according to claim 1, wherein the partition wall is deformed or displaced toward the toner retraction space when the toner conveyance space is filled with toner.   The toner retraction space is formed on a side opposite to a toner swell side accompanying a toner conveyance action in a cross-sectional direction generated by a rotation direction of the conveyance member and a bottom surface of the toner retraction space. The developing device according to claim 1 or 2.   An image forming apparatus comprising the developing device according to claim 1.

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