JP2009282189A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly supply a developer, even if the liquid level of the developer is lowered at one end side due to its being installed at an inclination. <P>SOLUTION: The developing device comprises: a developer carrier 11; a developer storage container 8, extending from one end to the other end, along the developer carrier 11 and storing therein a developer; a second developer conveying member 10 and supplying the developer to the developer carrier 11 provided in the inside the developer storage container; and a first developer conveying member 9 stirring the stored developer. The second developer conveying member 10 comprises a spiral blade 23 around a rotary shaft 22. The rotary shaft 22 is provided with a plurality of paddles 24, having a dimension which is not larger than the protruding dimension of the blade 23 but longer at both ends parts than at the center part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device and an electrophotographic type in which a toner image is transferred to a recording medium by a copying machine, a laser beam printer, a facsimile, or a complex machine using the developing device. The present invention relates to an image forming apparatus.

  In general, when an image forming apparatus is installed, it is inevitable that a slight inclination occurs. For this reason, the built-in developing device is also inclined, and the liquid level of the developer stored in the developer container may be lowered on one end side. In this case, at the position where the liquid level is low, the developer cannot be properly supplied to the developing roller by the second developer conveying member in the developer container, and there is a problem that uneven development density occurs.

  Conventionally, for example, the following configuration has been proposed in order to prevent development density unevenness caused by such inclination.

  In other words, the developer discharge mechanism section prevents the developer from being excessively discharged by intermittently discharging the developer in the developer (developer container) from the developer discharge opening. Are known (for example, see Patent Document 1).

  Further, as another configuration, a device in which the first transport member and the second transport member can be driven independently to prevent variation in the transport speed of the developer and to eliminate the deviation is known. (For example, see Patent Documents 2 and 3).

There is a configuration in which a paddle is provided on the outer periphery of the shaft portion of the second developer conveying member (see, for example, Patent Document 4).
JP 2006-293214 A JP 2006-293016 A JP 2003-280384 A Japanese Patent Application Laid-Open No. 6-167876

  However, although the configuration described in Patent Document 1 can prevent the developer from being supplied excessively, as described above, there is a problem in that it cannot cope with a case where supply is insufficient. is there.

  Further, the configurations described in Patent Documents 2 and 3 cannot cope with the case where the developer container is inclined due to the structure.

  Further, in the configuration described in Patent Document 4, the paddle merely agitates the developer in the developer container, and the supply amount to the developing roller decreases due to the lower liquid level of the developer. It is impossible to deal with cases.

  Accordingly, the present invention provides a developing device and an image forming apparatus that can be appropriately supplied with a developer even when the liquid level of the developer is lowered on one end side by being inclined. Let it be an issue.

As a means for solving the above problems, the present invention provides:
A developer carrier;
A developer container that extends from one end to the other along the developer carrying member, and that stores the developer; and
A first developer conveying member provided in the developer accommodating container and conveying the accommodated developer while stirring;
A second developer conveying member provided in the developer container and supplying the developer to the developer carrying member,
The second developer conveying member has a spiral blade extending from one end side toward the other end side around the rotation shaft, and a protrusion dimension of the blade or less, and is longer at both end portions than the center portion. And a plurality of paddles.

  With this configuration, the developer container is inclined with respect to the horizontal plane, and even if the developer level is lower than the reference position on one end side or the other end side, it protrudes from the center portion. Since the paddle having a large size is positioned, if the second developer transport member is operated, the amount of developer scraped up can be increased. Therefore, the amount of developer supplied by the second developer conveying member can be stabilized regardless of the decrease in the developer level.

  The developer container may have a developer supply port for supplying the developer and a developer discharge port for discharging the developer.

With this configuration,
The paddle of the second developer conveying member may be formed so that the projecting dimension gradually increases from the central portion toward both ends.
The paddle of the second developer conveying member may be formed so that the projecting dimension increases stepwise in a plurality of units from the central portion toward both ends.

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

  According to the present invention, since the protruding dimension of the paddle is larger at both end portions than at the central portion, even if the developer containing container is inclined and installed, the developer by the second developer conveying member It is possible to stabilize the supply amount throughout.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the following description, terms indicating specific directions and positions (for example, “up”, “down”, “side”, “end” and other terms including those terms) are used as necessary. These terms are used to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms.

  FIG. 1 shows an image forming apparatus 1 according to the present embodiment. The image forming apparatus 1 includes a photosensitive drum 2, a charging device 3, an exposure device 4, a developing device 5, a transfer device 6, and a cleaning device 7.

  The surface of the photosensitive drum 2 is uniformly charged by applying a charging potential by the charging device 3, and an electrostatic latent image is formed by being exposed to the laser light emitted from the exposure device 4. The electrostatic latent image is supplied with negatively charged toner from the developing device 5 and is visualized to become a toner image. This toner image is transferred onto the surface of the intermediate transfer belt 25 by a positive voltage (positive transfer potential) applied to the back side of the intermediate transfer belt 25 by the transfer device 6.

  The charging device 3 forms a predetermined surface potential on the surface of the photosensitive drum 2.

  The exposure device 4 irradiates the photosensitive drum 2 with laser light to form an electrostatic latent image corresponding to the image data.

  The developing device 5 contains a first developer transport member 9, a second developer transport member 10, and a developing roller 11 that is a developer carrier in a developer container 8.

  As shown in FIGS. 2 to 4, the developer storage container 8 is a long box-like one extending from one end to the other end, and the first storage portion 13 and the second storage portion are defined by a partition wall 12 extending in the longitudinal direction. 14 is divided into two in the vertical direction. A first developer conveying member 9 is accommodated in the first accommodating portion 13. The first accommodating portion 13 is appropriately replenished with a developer. Here, a two-component developer composed of a toner and a magnetic carrier is used as the developer. However, a developer further containing an external additive or the like may be used. On the other hand, the second developer transport member 10 and the developing roller 11 are accommodated in the second accommodating portion 14. The developer is appropriately discharged from the second storage portion 14. That is, a so-called trickle system is used in which replenishment and discharge are performed in units of developer. The first storage portion 13 and the second storage portion 14 communicate with each other through openings 15 formed at both ends of the partition wall 12 so that the developer can be circulated and stirred. Reference numeral 8a denotes a developer discharge port for discharging the developer.

  A part of the wall surface portion constituting the second accommodating portion 14 protrudes inward from the region where the second developer conveying member 10 is disposed, and serves as a guide protruding portion 16 along the outer peripheral surface of the developing roller 11. . A regulating member 17 is disposed on the upper surface of the guide protrusion 16 and is attached by a cover 18. The restricting member 17 is disposed so as to face the outer peripheral surface over the entire length from one end to the other end of the developing roller 11 (the surface facing the outer peripheral surface of the developing roller 11 is a restricting surface). The gap between the regulating member 17 and the developing roller 11 is set so as to regulate the developer supplied from the second developer conveying member 10 to the developing roller 11 and to have a predetermined constant thickness. The cover 18 is fixed to the guide protrusion 16 and extends to the vicinity of the photosensitive drum 2 along the outer peripheral surface of the developing roller 11.

  The developing roller 11 has a plurality of permanent magnets housed in a cylindrical sleeve. The sleeve is configured to rotate forward and backward in the circumferential direction by the sleeve driving means. Further, the permanent magnet is configured to rotate forward and backward in the circumferential direction along the inner peripheral surface of the sleeve by the magnet rotation driving means. As these driving means, it is preferable to use, for example, a servo motor, a stepping motor, or the like that can be driven in forward and reverse rotations and whose rotational position can be controlled.

  The first developer conveying member 9 has a configuration in which a spiral first blade 20 is formed on the outer peripheral surface of the first rotating shaft 19, and is rotated to transfer the developer from one end side to the other end side. Stir while stirring. A transport paddle 21 for transporting the developer to the second storage portion 14 is formed at one end portion of the first developer transport member 9 through one opening 15 formed in the developer storage container 8. Has been. In addition to the transport paddle 21, a stirring paddle (not shown) is formed on the first developer transport member 9 by projecting wires and plates from a plurality of locations on the outer peripheral surface of the first rotating shaft 19. You may make it do. The stirring paddle improves the stirring performance by preventing cross-linking from occurring in the developer conveyed by the spiral blade.

  Similar to the first developer conveying member 9, the second developer conveying member 10 has a configuration in which a spiral second blade 23 is formed on the outer peripheral surface of the second rotating shaft 22. However, supply paddles 24 are formed at a plurality of locations on the outer peripheral surface of the rotating shaft. The supply paddle 24 is formed so that the protrusion dimension of the second blade 23 is less than the protrusion dimension of the second rotating shaft 22 relative to the outer peripheral surface of the second rotation shaft 22 and the protrusion dimension is gradually increased at both ends compared to the center part. Has been. Here, a substantially rectangular flat plate is used for the supply paddle 24 and is formed alternately along the axial direction at two symmetrical positions on the outer peripheral surface of the second rotating shaft 22.

  As shown in FIG. 1, the transfer device 6 spans the intermediate transfer belt 25 between a pair of rollers (not shown), and the drive means (not shown) circulates and moves the intermediate transfer belt 25 in the arrow direction. A primary transfer portion and a secondary transfer portion. The primary transfer unit includes a primary transfer roller 26 that faces the photosensitive drum 2 with the intermediate transfer belt 25 sandwiched therebetween. The primary transfer roller 26 applies a positive voltage to the back surface of the intermediate transfer belt 25. The secondary transfer unit includes a secondary transfer roller (not shown) facing one of the rollers. The secondary transfer roller applies a positive voltage to the back surface of the intermediate transfer belt 25. The toner image transferred to the intermediate transfer belt 25 is transferred to a recording medium (for example, paper).

  The cleaning device 7 can come into contact with and separate from the intermediate transfer belt 25, and can collect toner remaining on the surface of the intermediate transfer belt 25 by approaching the cleaning device 7.

  Next, the operation of the image forming apparatus 1 having the above configuration, particularly the developing device 5 will be described.

  Color print data obtained by reading an image with an image reading unit (not shown) or image data output from a personal computer or the like is subjected to predetermined signal processing by a control unit (not shown). Input to the image forming apparatus 1. In the image forming apparatus 1, the laser beam is modulated based on the input image data and projected onto the photosensitive drum 2 to form an image latent image.

  In the developing device 5, the developer is supplied into the first storage portion 13 of the developer storage container 8. The replenished developer is sequentially conveyed in the axial direction by the first blade 20 by the rotation of the first developer conveying member 9. The developer that has moved to the one end side is conveyed to the second accommodating portion 14 through the opening 15 by the pressure of the conveyance and the function of the conveyance paddle 21. In the second storage portion 14, the second developer transport member 10 is transported in the axial direction by the second blade 23. Then, the developer that has moved to the one end side is returned to the inside of the first accommodating portion 13 through the opening 15 by the pressure due to the conveyance, and circulates.

  Incidentally, it is inevitable that the image forming apparatus 1 is installed in a slightly inclined state. When the developing device 5 is inclined in the longitudinal direction, as shown in FIG. 5, the liquid level of the developer in the second accommodating portion 14 also corresponds to the inclination (indicated by the angle α). . For this reason, the liquid level of the developer is lowered on one end side of the second developer conveying member 10. However, the developer is agitated by the supply paddle 24 and scraped up toward the developing roller 11. Therefore, it is possible to supply a sufficient amount of developer to the surface of the developing roller 11 in spite of a decrease in the liquid level of the developer, and no image defect occurs. On the other hand, on the other end side of the second developer conveying member 10, the developer level rises. For this reason, the developer is excessively supplied to the surface of the developing roller 11, but since the regulating member 17 is provided there, the excess developer is conveyed to the photosensitive drum side. There is nothing.

  Since the image latent image is formed on the photosensitive drum 2 as described above, a toner image corresponding to the image latent image is formed by supplying the developer from the developing roller 11. The formed toner image is primarily transferred onto the moving intermediate transfer belt 25 by being superposed on the moving intermediate transfer belt 25 by the action of the primary transfer roller 26. The toner image formed on the intermediate transfer belt 25 moves to the secondary transfer roller side as the intermediate transfer belt 25 moves.

  Further, paper is supplied from a paper supply unit (not shown). The supplied paper is conveyed between the secondary transfer roller and the intermediate transfer belt 25 by the conveyance roller, and the toner image formed on the intermediate transfer belt 25 is transferred.

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

  For example, the supply paddle 24 formed on the second developer conveying member 10 is formed so as to gradually increase its protruding dimension from the central portion toward both ends, but as shown in FIG. It is also possible to form so that the protruding dimension is increased step by step.

  Further, the supply paddle 24 does not change the projecting dimension from the second rotating shaft 22, but the outer diameter dimension itself of the second rotating shaft 22 remains the same as shown in FIG. May be gradually increased toward both ends.

  Further, instead of changing the outer diameter of the second rotating shaft 22, as shown in FIG. 8, the width (length in the axial direction) of the supply paddle 24 is gradually increased. May be. Similarly to FIG. 6, the width dimension may be increased step by step by a predetermined number.

  The shape of the supply paddle 24 is not limited to a rectangular flat plate, but may take various forms such as a triangle, a trapezoid, and a circle. For example, the protruding side edge portion may be formed so as to be linearly separated from the rotation axis.

  Further, the formation position of the supply paddle 24 may be any position as long as it does not interfere with the blades. Alternatively, the supply paddle 24 may be provided at equal intervals in the axial direction of the second rotary shaft 22 or unevenly. You may make it provide. The swivel pitch of the second blades 23 may be any suitable for the developer transport, and the interval between the supply paddles 24 may be changed according to the swivel pitch of the second blades 23. Further, the supply paddle 24 can be formed by shifting its position in the circumferential direction.

1 is a schematic view of an image forming apparatus according to an embodiment. FIG. 3 is a partial cross-sectional view illustrating a state where first and second developer transport members accommodated in the developer accommodating container of FIG. 1 are viewed from above. FIG. 3 is a partial cross-sectional view illustrating a state in which a second developer conveying member and a developing roller stored in the developer storage container of FIG. 1 are viewed from the side. FIG. 4 is an overall cross-sectional view illustrating a state in which a second developer conveying member and a developing roller housed in the developer container of FIG. 1 are viewed from the side. FIG. 5 is a cross-sectional view showing a state inclined from the angle of FIG. It is sectional drawing of the developer storage container which concerns on other embodiment. It is sectional drawing of the developer storage container which concerns on other embodiment. It is sectional drawing of the developer storage container which concerns on other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Photosensitive drum 3 ... Charging apparatus 4 ... Exposure apparatus 5 ... Developing apparatus 6 ... Transfer apparatus 7 ... Cleaning apparatus 8 ... Developer storage container 9 ... 1st developer conveyance member 10 ... 2nd developer Conveying member 11. Developing roller (developer carrier)
DESCRIPTION OF SYMBOLS 12 ... Partition wall 13 ... 1st accommodating part 14 ... 2nd accommodating part 15 ... Opening part 16 ... Guide protrusion 17 ... Restriction member 18 ... Cover 19 ... 1st rotating shaft 20 ... 1st blade | wing 21 ... Paddle 22 for conveyance 22 ... Second rotation shaft 23 ... second blade 24 ... supply paddle 25 ... intermediate transfer belt 26 ... primary transfer roller

Claims (5)

A developer carrier;
A developer container that extends from one end to the other along the developer carrying member, and that stores the developer; and
A first developer conveying member provided in the developer accommodating container and conveying the accommodated developer while stirring;
A second developer conveying member provided in the developer container and supplying the developer to the developer carrying member,
The second developer conveying member has a spiral blade extending from one end side toward the other end side around the rotation shaft, and a protrusion dimension of the blade or less, and is longer at both end portions than the center portion. A developing device comprising a plurality of paddles.   The developing device according to claim 1, wherein the developer container has a developer supply port for supplying the developer and a developer discharge port for discharging the developer.   3. The developing device according to claim 1, wherein the paddle of the second developer conveying member is formed so that a protruding dimension gradually increases from a central portion toward both ends.   3. The developing device according to claim 1, wherein the paddle of the second developer conveying member is formed so that a projecting dimension is increased stepwise in a plurality of units from the central portion toward both ends.   An image forming apparatus comprising the developing device according to claim 1.

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