Image forming apparatus

Abstract

The present invention provides an image forming apparatus. The toner supply unit includes an upper toner container, a lower toner container, a first vertical conveyance pipe, a second vertical conveyance pipe, a third vertical conveyance pipe, a first horizontal conveyance pipe, a second horizontal conveyance pipe, and a confluence portion, and includes a first spiral conveyor in the first horizontal conveyance pipe and a second spiral conveyor in the second horizontal conveyance pipe. A first axial distance between a first horizontal rotation axis of the first spiral conveyor and a third vertical pipe axis of the third vertical conveyance pipe and a second axial distance between a second horizontal rotation axis of the second spiral conveyor and the third vertical pipe axis are set to different values.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that forms an image on a thin sheet body. Background Art

[0002] Image forming apparatuses such as printers and copiers that typically employ an electrophotographic method include: a photosensitive drum that bears an electrostatic latent image; and a developing device that supplies toner to the photosensitive drum to make the electrostatic latent image appear as a toner image.

[0003] For example, there is known an image forming apparatus that includes a plurality of developing devices corresponding to respective color toners, and a plurality of toner supply units that supply toner to the respective developing devices. Each toner supply unit includes two toner containers. The toner discharged from the two toner containers is conveyed by two conveying members, and after converging with each other at a converging portion disposed on the downstream side, it reaches the developing device. Even when one of the toner containers becomes empty, toner can be supplied from the other toner container, so that the frequency and time of stopping the image forming operation due to the replacement of the toner container can be reduced.

[0004] In each toner supply unit, a technique for effectively converging the toner conveyed by the two conveying members at the converging portion has also been proposed. In this technique, the two conveying members are arranged in a V shape such that the area portion on the downstream side approaches the upstream side at the converging portion.

[0005] Due to the influence of the increase in the capacity of the toner container in response to high-speed printing and the reduction in the size of the apparatus, etc., sometimes the interval between adjacent developing devices is different from the interval between one of the toner containers of adjacent toner supply units. In this case, the angle formed by the two conveying members arranged in a V shape is different for each toner supply unit. Therefore, there is a problem that a configuration in which a drive unit for driving the two conveying members cannot be shared among a plurality of toner supply units is generated. Summary of the Invention

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide an image forming apparatus that can effectively converge toner and can share a drive unit for driving a plurality of conveying members among a plurality of toner supply units in a configuration including a toner supply unit that supplies toner to a developing device after converging the toner discharged from a plurality of toner containers through the conveyance of a plurality of conveying members.

[0007] An image forming apparatus according to an aspect of the present invention includes: a plurality of image forming units each having a photosensitive drum rotatable about a drum axis extending horizontally and a developing device for supplying toner to the photosensitive drum, the plurality of image forming units being arranged along an arrangement direction horizontally orthogonal to the drum axis; and a plurality of toner supply units provided corresponding to the plurality of image forming units respectively for supplying toner to the developing device. Each of the plurality of toner supply units includes: a first container and a second container capable of storing toner therein and discharging toner; a first vertical transfer pipe formed in a cylindrical shape having a peripheral wall surrounding a first vertical pipe axis extending vertically downward from the first container for guiding the toner discharged from the first container vertically downward along the first vertical pipe axis; a second vertical transfer pipe formed in a cylindrical shape having a peripheral wall surrounding a second vertical pipe axis extending vertically downward from the second container for guiding the toner discharged from the second container vertically downward along the second vertical pipe axis; a first horizontal transfer pipe formed in a cylindrical shape extending along a first horizontal direction intersecting the drum axis and the arrangement direction, connected to a lower end of the first vertical transfer pipe and having a first inlet through which toner flows in; a second horizontal transfer pipe formed in a cylindrical shape extending along a second horizontal direction at an acute angle with respect to the first horizontal direction, connected to a lower end of the second vertical transfer pipe and having a second inlet through which toner flows in; a first transfer member disposed in the first horizontal transfer pipe so as to be rotatable about a first horizontal rotation axis along the first horizontal direction for conveying the toner flowing into the first horizontal transfer pipe through the first inlet to the downstream side by rotation; a second transfer member disposed in the second horizontal transfer pipe so as to be rotatable about a second horizontal rotation axis along the second horizontal direction for conveying the toner flowing into the second horizontal transfer pipe through the second inlet to the downstream side by rotation; a confluence portion communicating with a downstream side portion of the first horizontal transfer pipe and a downstream side portion of the second horizontal transfer pipe respectively, internally receiving the toner conveyed by the first transfer member and the second transfer member and having a confluence discharge port for discharging the received toner; a third vertical transfer pipe formed in a cylindrical shape having a peripheral wall surrounding a third vertical pipe axis extending vertically downward from the confluence discharge port for guiding the toner discharged from the confluence portion through the confluence discharge port vertically downward along the third vertical pipe axis toward the developing device; and a transfer driving unit for generating a driving force for rotating the first transfer member and the second transfer member. In a plan view of the confluence portion as viewed from the vertical direction, the confluence discharge port is disposed between the first horizontal rotation axis and the second horizontal rotation axis, and a first axial distance between the first horizontal rotation axis and the third vertical pipe axis and a second axial distance between the second horizontal rotation axis and the third vertical pipe axis are set to take different values.

[0008] An image forming apparatus according to another aspect of the present invention includes: a plurality of image forming units each having a photosensitive drum rotatable about a drum axis extending horizontally and a developing device for supplying toner to the photosensitive drum, the plurality of image forming units being arranged along an arrangement direction horizontally orthogonal to the drum axis; and a plurality of toner replenishing units provided corresponding to the plurality of image forming units respectively for replenishing toner to the developing device, each of the plurality of toner replenishing units including: a first container and a second container capable of storing toner therein and discharging toner; a first vertical conveying pipe formed in a cylindrical shape having a peripheral wall surrounding a first vertical pipe axis extending vertically downward from the first container for guiding the toner discharged from the first container vertically downward along the first vertical pipe axis; a second vertical conveying pipe formed in a cylindrical shape having a peripheral wall surrounding a second vertical pipe axis extending vertically downward from the second container for guiding the toner discharged from the second container vertically downward along the second vertical pipe axis; a first horizontal conveying pipe formed in a cylindrical shape extending along a first horizontal direction intersecting the drum axis and the arrangement direction, connected to the lower end of the first vertical conveying pipe and having a first inlet for the toner to flow in; a second horizontal conveying pipe formed in a cylindrical shape extending along a second horizontal direction at an acute angle with respect to the first horizontal direction, connected to the lower end of the second vertical conveying pipe and having a second inlet for the toner to flow in; a first conveying member disposed in the first horizontal conveying pipe so as to be rotatable about a first horizontal rotation axis along the first horizontal direction for conveying the toner flowing into the first horizontal conveying pipe through the first inlet downstream by rotation; a second conveying member disposed in the second horizontal conveying pipe so as to be rotatable about a second horizontal rotation axis along the second horizontal direction for conveying the toner flowing into the second horizontal conveying pipe through the second inlet downstream by rotation; a converging portion communicating with a downstream portion of the first horizontal conveying pipe and a downstream portion of the second horizontal conveying pipe respectively for receiving therein the toner conveyed by the first conveying member and the second conveying member respectively and having a converging discharge port for discharging the received toner; and a third vertical conveying pipe formed in a cylindrical shape having a peripheral wall surrounding a third vertical pipe axis extending vertically downward from the converging discharge port for guiding the toner discharged from the converging portion through the converging discharge port vertically downward along the third vertical pipe axis toward the developing device.and a conveying drive unit that generates a driving force for rotating the first conveying member and the second conveying member. In a plan view of the confluence portion as viewed from the vertical direction, the confluence discharge port is disposed between the first horizontal rotation axis and the second horizontal rotation axis. A first axial distance between the first horizontal rotation axis and the third vertical tube axis and a second axial distance between the second horizontal rotation axis and the third vertical tube axis are set to the same value. The first vertical conveying tube or the third vertical conveying tube of each of the plurality of toner supply units is disposed at a different position in a direction along the drum axis.;

[0009] An image forming apparatus according to another aspect of the present invention includes: at least three image forming units each having a photosensitive drum rotatable about a drum axis extending horizontally and a developing device for supplying toner to the photosensitive drum, the at least three image forming units being arranged along an arrangement direction horizontally orthogonal to the drum axis; and at least three toner supply units respectively provided corresponding to the at least three image forming units for supplying toner to the developing device, the at least three toner supply units each including: a first container and a second container capable of storing toner therein and discharging toner; a first vertical transfer pipe formed in a cylindrical shape having a peripheral wall surrounding a first vertical pipe axis extending vertically downward from the first container for guiding the toner discharged from the first container vertically downward along the first vertical pipe axis; a second vertical transfer pipe formed in a cylindrical shape having a peripheral wall surrounding a second vertical pipe axis extending vertically downward from the second container for guiding the toner discharged from the second container vertically downward along the second vertical pipe axis; a first horizontal transfer pipe formed in a cylindrical shape extending along a first horizontal direction intersecting the drum axis and the arrangement direction, connected to a lower end of the first vertical transfer pipe and having a first inlet for the toner to flow in; a second horizontal transfer pipe formed in a cylindrical shape extending along a second horizontal direction at an acute angle with respect to the first horizontal direction, connected to a lower end of the second vertical transfer pipe and having a second inlet for the toner to flow in; a first transfer member arranged in the first horizontal transfer pipe so as to be rotatable about a first horizontal rotation axis along the first horizontal direction for conveying the toner flowing into the first horizontal transfer pipe through the first inlet downstream by rotation; a second transfer member arranged in the second horizontal transfer pipe so as to be rotatable about a second horizontal rotation axis along the second horizontal direction for conveying the toner flowing into the second horizontal transfer pipe through the second inlet downstream by rotation; a confluence portion communicating with downstream portions of the first horizontal transfer pipe and the second horizontal transfer pipe respectively for receiving therein the toner conveyed by the first transfer member and the second transfer member and having a confluence discharge port for discharging the received toner; and a third vertical transfer pipe formed in a cylindrical shape having a peripheral wall surrounding a third vertical pipe axis extending vertically downward from the confluence discharge port for guiding the toner discharged from the confluence portion through the confluence discharge port vertically downward along the third vertical pipe axis toward the developing device.and a conveyance driving unit that generates a driving force for rotating the first conveyance member and the second conveyance member. When viewed from above the confluence portion in a plan view in the vertical direction, the confluence discharge port is disposed between the first horizontal rotation axis and the second horizontal rotation axis, and a first axial distance between the first horizontal rotation axis and the third vertical tube axis and a second axial distance between the second horizontal rotation axis and the third vertical tube axis are set to the same value. An interval in the arrangement direction between adjacent first vertical conveyance tubes or an interval in the arrangement direction between the third vertical conveyance tubes among the at least three toner replenishment units is set to a different value.; BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a cross-sectional view showing the internal structure of an image forming apparatus according to an embodiment of the present invention.

[0011] Figure 2 is a perspective view of a toner replenishment unit included in the image forming apparatus.

[0012] Figure 3 is a front view of the toner replenishment unit.

[0013] Figure 4 is a side view of the toner replenishment unit.

[0014] Figure 5 is a perspective view of a state in which a toner container is removed from the toner replenishment unit.

[0015] Figure 6 is a view of the toner replenishment unit in a state where the toner container is removed, as viewed from above.

[0016] Figure 7 is a perspective view of a first conveyance member and a second conveyance member included in the toner replenishment unit.

[0017] Figure 8 is a perspective view showing an enlarged vicinity of a conveyance driving unit included in the toner replenishment unit.

[0018] Figure 9 is a block diagram of a control unit of the image forming apparatus.

[0019] Figure 10 is a view of a toner replenishment unit according to a modified embodiment of the present invention, as viewed from above. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In the present embodiment, as an example of the image forming apparatus, a tandem color printer is illustrated. The image forming apparatus may be, for example, a copying machine, a facsimile machine, or a digital multi-function machine thereof.

[0021] Figure 1 is a cross-sectional view showing the internal structure of the image forming apparatus 10. The image forming apparatus 10 includes a device main body 11 having a box-shaped frame structure. Inside the device main body 11, a paper feeding unit 12 for supplying a sheet body P, an image forming unit 13 for forming a toner image to be transferred onto the sheet body P supplied from the paper feeding unit 12, an intermediate transfer unit 14 for primarily transferring the toner image, a secondary transfer roller 145, and a fixing unit 16 for performing a process of fixing the unfixed toner image formed on the sheet body P onto the sheet body P are provided. Further, a paper discharging unit 171 is provided above the device main body 11, and the sheet body P that has undergone the fixing process by the fixing unit 16 is discharged to the paper discharging unit 171.

[0022] Inside the device main body 11, a sheet body conveyance path 111 extending in the vertical up-and-down direction is also formed at a position on the right side of the image forming unit 13. A pair of conveyance rollers for conveying the sheet body P to an appropriate position is provided in the sheet body conveyance path 111. In addition, an alignment roller pair 113 for correcting the skew of the sheet body P and feeding the sheet body P into the nip portion of the secondary transfer described later at a prescribed timing is also provided on the upstream side of the nip portion in the sheet body conveyance path 111. The sheet body conveyance path 111 is a conveyance path for conveying the sheet body P from the paper feeding unit 12 via the image forming unit 13 (secondary transfer nip portion) and the fixing unit 16 to the paper discharging unit 171.

[0023] The paper feeding unit 12 includes a paper feed tray 121 and a paper feed roller 122. The paper feed tray 121 is detachably mounted at a lower position of the device main body 11 and stores a stack of multiple sheet bodies P. The paper feed roller 122 pulls out the topmost sheet body P1 of the stack of paper stored in the paper feed tray 121 one by one.

[0024] The image forming unit 13 forms a toner image to be transferred onto the sheet body P, and a plurality (at least three) of units are provided to form toner images of different colors. In the present embodiment, as the plurality of image forming units 13, from the upstream side in the rotation direction of the intermediate transfer belt 141 described later toward the downstream side (from Figure 1In the arrangement direction from left to right as shown, there are provided a first image forming unit 13Y that uses yellow (Y) toner and is arranged corresponding to toners of multiple colors, a second image forming unit 13C that uses cyan (C) toner, a third image forming unit 13M that uses magenta (M) toner, and a fourth image forming unit 13BK that uses black (BK) toner. In other words, the first to fourth image forming units 13Y, 13C, 13M, and 13BK of the multiple image forming units 13 are arranged along the arrangement direction (left - right direction) that is horizontally orthogonal to the drum axis 20A of the photosensitive drum 20 described later. Since the first to fourth image forming units 13Y, 13C, 13M, and 13BK have the same structure except for the color of the toner, they are sometimes collectively referred to as the image forming unit 13. Each image forming unit 13 includes a photosensitive drum 20, a charging device 21 arranged around the photosensitive drum 20, a developing device 23, and a cleaning device 25. In addition, an exposure device 22 shared by each image forming unit 13 is arranged below the image forming unit 13.

[0025] The photosensitive drum 20 is rotationally driven around a specified drum axis 20A that extends horizontally (along the front - back direction), allowing an electrostatic latent image to be formed on its circumferential surface and carrying a toner image. The charging device 21 uniformly charges the surface of the photosensitive drum 20. The exposure device 22 has various optical system devices such as a light source, a polyhedral prism, a mirror, and a deflection mirror, and irradiates the circumferential surface of the uniformly charged photosensitive drum 20 with light modulated based on image data to form an electrostatic latent image. The cleaning device 25 cleans the circumferential surface of the photosensitive drum 20 after the toner image is transferred. In the present embodiment, the photosensitive drum 20, the charging device 21, and the cleaning device 25 are integrally formed to constitute a drum unit 2( Figure 1 ).

[0026] In order to develop (make visible) the electrostatic latent image formed on the photosensitive drum 20, the developing device 23 supplies toner to the circumferential surface of the photosensitive drum 20. The developing device 23 stores magnetic single - component toner as a developer. In addition, in the present embodiment, the toner has the characteristic of being positively charged. In other embodiments, the developing device 23 may also adopt other developing methods such as a two - component developer method composed of toner and carrier or a non - magnetic single - component developer method.

[0027] The intermediate transfer unit 14 is arranged above each image forming unit 13. The intermediate transfer unit 14 includes an intermediate transfer belt 141, a driving roller 142, a driven roller 143, and a primary transfer roller 24.

[0028] The intermediate transfer belt 141 is an annular belt-shaped rotating body, and is installed on the driving roller 142 and the driven roller 143 in such a manner that its peripheral surface side is in contact with the peripheral surfaces of the respective photosensitive drums 20. The intermediate transfer belt 141 is rotationally driven in one direction, and a toner image transferred from the photosensitive drum 20 is carried on its surface.

[0029] The driving roller 142 is installed on the left end side of the intermediate transfer unit 14 with the intermediate transfer belt 141 tensioned, and rotates and drives the intermediate transfer belt 141. The driving roller 142 is composed of a metal roller. The driven roller 143 is installed on the right end side of the intermediate transfer unit 14 with the intermediate transfer belt 141 tensioned. The driven roller 143 applies tension to the intermediate transfer belt 141.

[0030] The primary transfer roller 24 forms a primary transfer nip portion with the photosensitive drum 20 across the intermediate transfer belt 141, and primarily transfers the toner image on the photosensitive drum 20 to the intermediate transfer belt 141. The primary transfer roller 24 is arranged opposite to the respective photosensitive drums 20 of each color.

[0031] The secondary transfer roller 145 is arranged opposite to the driving roller 142 across the intermediate transfer belt 141. The secondary transfer roller 145 forms a secondary transfer nip portion by being in pressure contact with the peripheral surface of the intermediate transfer belt 141. The toner image primarily transferred to the intermediate transfer belt 141 is secondarily transferred to the sheet body P supplied from the paper supply unit 12 in the secondary transfer nip portion. The intermediate transfer unit 14 and the secondary transfer roller 145 in the present embodiment constitute a transfer portion. The transfer portion transfers the toner images formed in the respective image forming units 13 from the respective photosensitive drums 20 to the sheet body P.

[0032] The sheet body P supplied to the fixing unit 16 is heated and pressed through the fixing nip portion. Thus, the toner image transferred to the sheet body P in the secondary transfer nip portion is fixed on the sheet body P.

[0033] The paper discharge portion 171 is formed by a depression at the top of the apparatus main body 11. The sheet body P that has undergone the fixing process is discharged onto the paper discharge portion 171 through a sheet body conveyance passage 111 extending from the upper part of the fixing unit 16.

[0034] Figures 2 to 4 It is a diagram showing the toner replenishing unit 5 provided in the image forming apparatus 10. Figure 2 It is a perspective view. Figure 3 It is a front view. Figure 4 It is a side view. In addition, Figure 5 and Figure 6 It is a diagram showing the state in which the toner containers 50 and 51 are removed in the toner replenishing unit 5. Figure 5 It is a perspective view. Figure 6 It is a view observed from above.

[0035] The image forming apparatus 10 further includes a plurality of (at least three) toner supply units 5 provided corresponding to the plurality of image forming units 13 respectively. In the present embodiment, as the plurality of toner supply units 5, there are provided a first toner supply unit 5Y corresponding to the first image forming unit 13Y, a second toner supply unit 5C corresponding to the second image forming unit 13C, a third toner supply unit 5M corresponding to the third image forming unit 13M, and a fourth toner supply unit 5BK corresponding to the fourth image forming unit 13BK. The first to fourth toner supply units 5Y, 5C, 5M, 5BK of the plurality of toner supply units 5 are arranged along the same arrangement direction (left - right direction) as the image forming units 13. The first to fourth toner supply units 5Y, 5C, 5M, 5BK have the same structure except for the different toner colors used, and thus are sometimes collectively referred to as the toner supply unit 5.

[0036] Each toner supply unit 5 is a unit that supplies toner to the developing device 23 of the corresponding image forming unit 13. Each toner supply unit 5 includes an upper toner container 50 (first container) and a lower toner container 51 (second container).

[0037] The upper toner container 50 and the lower toner container 51 extend in the front - rear direction along the drum axis 20A of the photosensitive drum 20, and can store and discharge toner inside. The upper toner container 50 and the lower toner container 51 are installed on the apparatus main body 11 in the installation direction DM ( Figure 2 the rear direction) along the drum axis 20A of the photosensitive drum 20. In the present embodiment, the upper toner container 50 has a cylindrical shape, and a spiral slit 50A extending spirally along the axial direction is formed on its outer peripheral surface. Similarly, the lower toner container 51 has a cylindrical shape, and a spiral slit 51A extending spirally along the axial direction is formed on its outer peripheral surface. The spiral slits 50A, 51A form spiral protrusions protruding into the internal spaces of the upper toner container 50 and the lower toner container 51. And, by rotating the upper toner container 50 and the lower toner container 51 respectively, the toner inside is conveyed rearward through the spiral protrusions.

[0038] In a state where the upper toner container 50 is installed on the apparatus main body 11, it is supported by an upper container support portion 60 fixed to the apparatus main body 11 and is positioned. The upper toner container 50 has a fixing portion 50B and a first container gear 50C. The fixing portion 50B does not rotate, and the portion of the upper toner container 50 in front of the fixing portion 50B can rotate relative to the fixing portion 50B. The first container gear 50C is a gear fixed to the outer peripheral portion of the upper toner container 50 in front of the fixing portion 50B. By transmitting a rotational force to the first container gear 50C, the front portion of the upper toner container 50 rotates.

[0039] The lower toner container 51 is also positioned while being supported by a lower container support portion 61 fixed to the apparatus main body 11 in a state of being installed in the apparatus main body 11. The lower toner container 51 has a fixing portion 51B and a second container gear 51C. The fixing portion 51B does not rotate, and a portion of the lower toner container 51 that is forward of the fixing portion 51B can rotate relative to the fixing portion 51B. The second container gear 51C is a gear fixed to the outer peripheral portion of the lower toner container 51 at the front portion of the fixing portion 51B. By transmitting a rotational force to the second container gear 51C, the front portion of the lower toner container 51 rotates.

[0040] In addition, the upper toner container 50 has an unillustrated first toner discharge port formed in the front end side in the mounting direction DM of the fixing portion 50B, and the lower toner container 51 has an unillustrated second toner discharge port formed in the front end side in the mounting direction DM of the fixing portion 51B. Toner is discharged from these toner discharge ports. Further, the upper toner container 50 and the lower toner container 51 have gates for sealing the respective toner discharge ports. When the upper toner container 50 is installed in the upper container support portion 60 and the lower toner container 51 is installed in the lower container support portion 61, these gates slide and move to open the respective toner discharge ports. In addition, the upper toner containers 50 and the lower toner containers 51 included in each of the plurality of toner supply units 5 are arranged in Figure 1 the container space S of the apparatus main body 11.

[0041] In addition, the upper toner container 50 and the lower toner container 51 are formed to have the same length. Further, the upper toner container 50 and the lower toner container 51 are formed to have the same length for each of the plurality of toner supply units 5. That is, all the upper toner containers 50 and the lower toner containers 51 included in each of the plurality of toner supply units 5 are formed to have the same length.

[0042] In each toner supply unit 5, the upper toner container 50 is located above the lower toner container 51 and is arranged so as to overlap a part of the lower toner container 51 in a plan view observed from the vertical direction (up and down direction). That is, in a case of observing in the front - rear direction along the drum axis 20A of the photosensitive drum 20, the upper toner containers 50 and the lower toner containers 51 of the plurality of toner supply units 5 are arranged in a staggered manner. Thereby, an increase in the width of each toner supply unit 5 in the horizontal direction (left - right direction) is suppressed, and the toner supply unit 5 can be made compact.

[0043] Each toner supply unit 5 further includes a first vertical conveying pipe 52, a second vertical conveying pipe 53, a third vertical conveying pipe 54, a first horizontal conveying pipe 55, a second horizontal conveying pipe 56, a confluence portion 57, a first screw conveyor 58 (first conveying member), a second screw conveyor 59 (second conveying member), and a conveying drive unit 70.

[0044] The first vertical conveying pipe 52 is a tubular body formed with a peripheral wall surrounding a first vertical pipe axis 52A extending vertically downward from the upper toner container 50. The first vertical pipe axis 52A serves as the central axis of the first vertical conveying pipe 52. In a state where the upper toner container 50 is supported by the upper container support portion 60, the first vertical conveying pipe 52 communicates with a first toner discharge port formed in a fixing portion 50B of the upper toner container 50. Therefore, the first vertical conveying pipe 52 guides the toner discharged from the upper toner container 50 vertically downward along the first vertical pipe axis 52A.

[0045] The second vertical conveying pipe 53 is a cylindrical body formed with a peripheral wall surrounding a second vertical pipe axis 53A extending vertically downward from the lower toner container 51. The second vertical pipe axis 53A serves as the central axis of the second vertical conveying pipe 53. In a state where the lower toner container 51 is supported by the lower container support portion 61, the second vertical conveying pipe 53 communicates with a second toner discharge port formed in a fixing portion 51B of the lower toner container 51. Therefore, the second vertical conveying pipe 53 guides the toner discharged from the lower toner container 51 vertically downward along the second vertical pipe axis 53A.

[0046] In addition, with the upper toner container 50 disposed above the lower toner container 51, the length of the first vertical conveying pipe 52 along the first vertical pipe axis 52A is set to be greater than the length of the second vertical conveying pipe 53 along the second vertical pipe axis 53A.

[0047] In addition, in each toner supply unit 5, the first vertical conveyance pipe 52 and the second vertical conveyance pipe 53 are arranged at the same position in the front-rear direction along the drum axis 20A. Accordingly, the upper toner container 50 communicating with the first vertical conveyance pipe 52 and the lower toner container 51 communicating with the second vertical conveyance pipe 53 are arranged at the same position in the front-rear direction along the drum axis 20A. Further, in the plurality of toner supply units 5, the respective first vertical conveyance pipes 52 and the respective second vertical conveyance pipes 53 are arranged at the same position in the front-rear direction along the drum axis 20A. That is, all the first vertical conveyance pipes 52 and the second vertical conveyance pipes 53 provided in the plurality of toner supply units 5 are arranged at the same position in the front-rear direction along the drum axis 20A. Accordingly, all the upper toner containers 50 and the lower toner containers 51 provided in the plurality of toner supply units 5 are arranged at the same position in the front-rear direction along the drum axis 20A. Thereby, the front ends and the rear ends of all the upper toner containers 50 and the lower toner containers 51 provided in the plurality of toner supply units 5 are aligned in the front-rear direction. Accordingly, the appearance of the plurality of toner supply units 5 is improved.

[0048] In addition, between adjacent toner supply units 5, the intervals in the arrangement direction (left-right direction) between the first vertical conveyance pipes 52 and the intervals in the arrangement direction (left-right direction) between the second vertical conveyance pipes 53 are set to the same value. Refer to Figure 6 For specific description, the interval PC1 between the first vertical conveyance pipes 52 in the first toner supply unit 5Y and the second toner supply unit 5C, the interval PC2 between the first vertical conveyance pipes 52 in the second toner supply unit 5C and the third toner supply unit 5M, and the interval PC3 between the first vertical conveyance pipes 52 in the third toner supply unit 5M and the fourth toner supply unit 5BK are set to the same value. Accordingly, the intervals in the arrangement direction (first container interval) between the upper toner containers 50 between adjacent toner supply units 5 are the same, and the intervals in the arrangement direction (second container interval) between the lower toner containers 51 are the same. In other words, the plurality of upper toner containers 50 are arranged at equal intervals in the arrangement direction, and the plurality of lower toner containers 51 are arranged at equal intervals in the arrangement direction.

[0049] The first horizontal transfer pipe 55 is a tubular pipe body formed to extend along a first horizontal direction D1 that intersects the arrangement direction (left - right direction) of the drum axis 20A of the photosensitive drum 20 and the toner supply unit 5 on a horizontal plane. Therefore, the first horizontal transfer pipe 55 extends in the first horizontal direction D1 that intersects the upper toner container 50 extending along the drum axis 20A. The first horizontal transfer pipe 55 is connected to the lower end of the first vertical transfer pipe 52 and has a first inlet 55A formed at its connection portion. The toner discharged from the upper toner container 50 and falling into the first vertical transfer pipe 52 flows into the first horizontal transfer pipe 55 through the first inlet 55A.

[0050] The second horizontal transfer pipe 56 is a tubular pipe body formed to extend in a second horizontal direction D2 at an acute angle with respect to the first horizontal direction D1. Therefore, the second horizontal transfer pipe 56 extends in the second horizontal direction D2 that intersects the lower toner container 51 extending along the drum axis 20A. Specifically, the first horizontal transfer pipe 55 and the second horizontal transfer pipe 56 are arranged in a V - shape such that the downstream - side region portions approach each other at the confluence portion 57 with an acute angle formed between them. The second horizontal transfer pipe 56 is connected to the lower end of the second vertical transfer pipe 53 and has a second inlet 56A formed at its connection portion. The toner discharged from the lower toner container 51 and falling into the second vertical transfer pipe 53 flows into the second horizontal transfer pipe 56 through the second inlet 56A.

[0051] The first horizontal transfer pipe 55 and the second horizontal transfer pipe 56 are supported from the lower side by a transfer pipe support portion 62.

[0052] The first screw conveyor 58 is a conveying member arranged in the first horizontal transfer pipe 55 so as to be rotatable about a first horizontal rotation axis 58A along the first horizontal direction D1. The first screw conveyor 58 conveys the toner flowing into the first horizontal transfer pipe 55 through the first inlet 55A to the downstream side toward the confluence portion 57 by rotating about the first horizontal rotation axis 58A. Refer to Figure 7 The details of the first screw conveyor 58 will be described. The first screw conveyor 58 has a first shaft 581, a first main conveying blade 582, a first upstream - side sub - conveying blade 583, a first scraper 584, and a first downstream - side sub - conveying blade 585.

[0053] The first shaft 581 is arranged on the first horizontal rotation shaft 58A and is a shaft that rotates by the driving force of a conveying drive unit 70 described later. The first main conveying blade 582 is a spiral blade and is arranged on the first shaft 581 from a position directly below the first inlet 55A of the first horizontal conveying pipe 55 toward the confluence part 57. The first main conveying blade 582 rotates along with the rotation of the first shaft 581, thereby conveying the toner toward the confluence part 57 to the downstream side. The first upstream side sub-conveying blade 583 is a spiral blade and is arranged on the first shaft 581 on the upstream side of the toner conveying direction relative to the first main conveying blade 582. The first upstream side sub-conveying blade 583 conveys the toner in the same direction as the first main conveying blade 582, preventing the toner from being conveyed toward the conveying drive unit 70 side. The first scraping blade 584 is a scraping blade arranged in the confluence part 57 on the downstream side of the first main conveying blade 582 in the toner conveying direction on the first shaft 581. The first scraping blade 584 rotates along with the first shaft 581, thereby sending the toner conveyed from the first main conveying blade 582 to the confluence part 57 to the confluence discharge port 57A. The first downstream side sub-conveying blade 585 is a spiral blade and is arranged on the first shaft 581 on the downstream side of the toner conveying direction relative to the first scraping blade 584. The first downstream side sub-conveying blade 585 prevents the toner from entering the downstream end side of the first horizontal conveying pipe 55 by conveying the toner in the direction opposite to the first main conveying blade 582.

[0054] The second spiral conveyor 59 is a conveying member arranged in the second horizontal conveying pipe 56 in a manner capable of rotating around a second horizontal rotation shaft 59A along the second horizontal direction D2. The second spiral conveyor 59 conveys the toner flowing into the second horizontal conveying pipe 56 through the second inlet 56A to the downstream side toward the confluence part 57. Refer to Figure 7 The details of the second spiral conveyor 59 will be described. The second spiral conveyor 59 includes a second shaft 591, a second main conveying blade 592, a second upstream side sub-conveying blade 593, a second scraping blade 594, and a second downstream side sub-conveying blade 595.

[0055] The second shaft 591 is arranged on the second horizontal rotation shaft 59A and is a shaft that rotates by the driving force of the conveying drive unit 70. The second main conveying blade 592 is a spiral blade and is arranged on the second shaft 591 from a position directly below the second inlet 56A of the second horizontal conveying pipe 56 toward the confluence portion 57. The second main conveying blade 592 rotates along with the rotation of the second shaft 591, thereby conveying the toner toward the confluence portion 57 to the downstream side. The second upstream side sub-conveying blade 593 is a spiral blade and is arranged on the second shaft 591 on the upstream side of the toner conveying direction relative to the second main conveying blade 592. The second upstream side sub-conveying blade 593 conveys the toner in the same direction as the second main conveying blade 592, preventing the toner from being conveyed toward the conveying drive unit 70 side. The second squeegee 594 is arranged in the confluence portion 57 on the second shaft 591 on the downstream side of the toner conveying direction relative to the second main conveying blade 592. The second squeegee 594 rotates along with the rotation of the second shaft 591, thereby sending the toner conveyed from the second main conveying blade 592 to the confluence portion 57 to the confluence discharge port 57A. The second downstream side sub-conveying blade 595 is a spiral blade and is arranged on the second shaft 591 on the downstream side of the toner conveying direction relative to the second squeegee 594. The second downstream side sub-conveying blade 595 prevents the toner from entering the downstream end side of the second horizontal conveying pipe 56 by conveying the toner in the direction opposite to that of the second main conveying blade 592.

[0056] As described above, the first horizontal conveying pipe 55 extends along the first horizontal direction D1, and the second horizontal conveying pipe 56 extends along the second horizontal direction D2 at an acute angle with respect to the first horizontal direction D1. Therefore, as Figure 6 shown, the first spiral conveyor 58 in the first horizontal conveying pipe 55 and the second spiral conveyor 59 in the second horizontal conveying pipe 56 are arranged in a V-shaped configuration in which the region part on the downstream side approaches the confluence portion 57 with the angle θ formed by the respective first horizontal rotation shaft 58A and the second horizontal rotation shaft 59A being an acute angle with respect to the upstream side. Thereby, the toner conveyed by the first spiral conveyor 58 and the second spiral conveyor 59 can be effectively confluent at the confluence portion 57.

[0057] The confluence portion 57 is respectively communicated with the downstream side portion of the toner conveying direction of the first horizontal conveying pipe 55 and the downstream side portion of the toner conveying direction of the second horizontal conveying pipe 56. The confluence portion 57 has a circular confluence discharge port 57A. As Figure 6 shown, in the plan view of observing the confluence portion 57 from the vertical direction, the confluence discharge port 57A is arranged between the first horizontal rotation shaft 58A and the second horizontal rotation shaft 59A. The confluence portion 57 internally receives the toner conveyed by the first spiral conveyor 58 and the second spiral conveyor 59, and discharges the received toner through the confluence discharge port 57A.

[0058] The third vertical transfer pipe 54 is formed as a cylindrical pipe body having a peripheral wall surrounding a third vertical pipe axis 54A extending vertically downward from the confluence discharge port 57A. The third vertical pipe axis 54A serves as the central axis of the third vertical transfer pipe 54. One end of the third vertical transfer pipe 54 is connected to the opening edge of the confluence discharge port 57A in the confluence portion 57, and the other end is connected to the developing device 23. Accordingly, the third vertical transfer pipe 54 guides the toner discharged from the confluence portion 57 through the confluence discharge port 57A vertically downward along the third vertical pipe axis 54A toward the developing device 23.

[0059] Among the plurality of toner supply units 5, the third vertical transfer pipes 54 are respectively arranged at the same positions in the front-back direction along the drum axis 20A. Accordingly, the developing devices 23 of respective colors communicating with the third vertical transfer pipes 54 are arranged at the same positions in the front-back direction along the drum axis 20A.

[0060] In addition, between adjacent toner supply units 5, the intervals in the arrangement direction (left-right direction) between the third vertical transfer pipes 54 are set to the same value. Refer to Figure 6 For specific description, the interval PD1 between the third vertical transfer pipes 54 in the first toner supply unit 5Y and the second toner supply unit 5C, the interval PD2 between the third vertical transfer pipes 54 in the second toner supply unit 5C and the third toner supply unit 5M, and the interval PD3 between the third vertical transfer pipes 54 in the third toner supply unit 5M and the fourth toner supply unit 5BK are set to the same value. Accordingly, the intervals in the arrangement direction (developing device intervals) between the developing devices 23 adjacent to each other by color are the same. In other words, the developing devices 23 of respective colors are arranged at equal intervals along the arrangement direction.

[0061] The conveyance driving unit 70 generates a driving force for rotating the first spiral conveyor 58 and the second spiral conveyor 59. The conveyance driving unit 70 is arranged on the upstream side in the toner conveyance direction of the first horizontal transfer pipe 55 and the second horizontal transfer pipe 56 and on the side opposite to the confluence portion 57. Refer to Figure 8 Details of the conveyance driving unit 70 will be described. The conveyance driving unit 70 includes a motor 71 and a drive transmission system including a worm gear 72, a drive gear 73, a swing gear 74, a first input gear 75, a second input gear 76, a first transmission gear 77, a second transmission gear 78, and a third transmission gear 79.

[0062] The motor 71 is a brushed motor capable of rotating in a first rotation direction and a second rotation direction opposite to the first rotation direction. The motor 71 is disposed between the drive transmission systems of the adjacent toner supply units 5. For example, the motor 71 of the first toner supply unit 5Y is disposed between the drive transmission system of the first toner supply unit 5Y and the drive transmission system of the second toner supply unit 5C. The rotation, stop, and rotation direction of the motor 71 are controlled by the drive control unit 801 of the control unit 80 described later. The worm gear 72 is connected to the output shaft of the motor 71. Corresponding to the rotation direction of the motor 71, the worm gear 72 can also rotate in different rotation directions. The drive gear 73 is coaxially connected to the worm gear 72 and is a gear that outputs the rotational driving force of the motor 71 via the worm gear 72. The drive gear 73 can rotate in different rotation directions corresponding to the rotation direction of the motor 71.

[0063] The first input gear 75 is a gear fixed to one end of the first shaft 581 of the first screw conveyor 58 and inputs the rotational driving force of the motor 71 to the first screw conveyor 58. The first input gear 75 is a conical bevel gear inclined corresponding to the angle θ formed by the first horizontal rotation shaft 58A and the second horizontal rotation shaft 59A. The first input gear 75 meshes with the bevel gear, i.e., the third transmission gear 79. The third transmission gear 79 meshes with the second transmission gear 78, and the first transmission gear 77 is disposed coaxially with the second transmission gear 78. The second input gear 76 is a gear fixed to one end of the second shaft 591 of the second screw conveyor 59 and inputs the rotational driving force of the motor 71 to the second screw conveyor 59.

[0064] The swing gear 74 is a gear disposed between the second input gear 76 and the first transmission gear 77 and meshes with the drive gear 73. The swing gear 74 is a gear capable of swinging between a first position and a second position according to the rotation direction of the drive gear 73, i.e., according to the rotation direction of the motor 71. The swing gear 74 meshes with the first transmission gear 77 at the first position and meshes with the second input gear 76 at the second position.

[0065] Assume the case where the swing gear 74 swings to the first position and meshes with the first transmission gear 77 when the motor 71 rotates in the first rotation direction. In this case, the rotational driving force of the motor 71 in the first rotation direction is transmitted in the order of the first transmission gear 77, the second transmission gear 78, and the third transmission gear 79. Thereby, the first input gear 75 meshing with the third transmission gear 79 rotates, and along with the rotation of the first input gear 75, the first screw conveyor 58 rotates. That is, the swing gear 74 allows the rotation of the first screw conveyor 58 at the first position.

[0066] On the other hand, assume a case where the swing gear 74 swings to the second position and meshes with the second input gear 76 according to the rotation of the motor 71 in the second rotation direction. In this case, the rotational driving force of the motor 71 in the second rotation direction is transmitted to the second input gear 76. As a result, the second input gear 76 rotates, and along with the rotation of the second input gear 76, the second screw conveyor 59 rotates. That is, the swing gear 74 allows the rotation of the second screw conveyor 59 at the second position.

[0067] By swinging the swing gear 74 according to the rotation direction of the motor 71, the transmission of the rotational driving force to the first screw conveyor 58 and the second screw conveyor 59 is switched. Thus, it is possible to selectively rotate the first screw conveyor 58 and the second screw conveyor 59 using the rotational driving force of a single motor 71. Therefore, the toner supply unit 5 can be realized compactly and at low cost.

[0068] In addition, the conveying drive unit 70 is not limited to the configuration of the swing gear 74. For example, the conveying drive unit 70 may be configured to include a first one-way clutch provided on the first shaft 581 of the first screw conveyor 58 and a second one-way clutch provided on the second shaft 591 of the second screw conveyor 59. In this case, the first one-way clutch allows the rotation of the first screw conveyor 58 when the motor 71 rotates in the first rotation direction, while restricting the rotation of the first screw conveyor 58 when the motor 71 rotates in the second rotation direction. The second one-way clutch allows the rotation of the second screw conveyor 59 when the motor 71 rotates in the second rotation direction, while restricting the rotation of the second screw conveyor 59 when the motor 71 rotates in the first rotation direction. In the conveying drive unit 70 having such a configuration, according to the rotation direction of the motor 71, the transmission of the rotational driving force to the first screw conveyor 58 and the second screw conveyor 59 is switched by the one-way clutch. Thus, it is possible to selectively rotate the first screw conveyor 58 and the second screw conveyor 59 using the rotational driving force of a single motor 71. Therefore, the toner supply unit 5 can be realized compactly and at low cost.

[0069] As described above, in the image forming apparatus 10 of the present embodiment, the toner supply units 5 are provided corresponding to the developing devices 23 of respective colors. In each toner supply unit 5, the toner container 50 and the lower toner container 51 are arranged corresponding to the developing device 23. The toner discharged from the upper toner container 50 flows into the first horizontal transfer pipe 55 through the first vertical transfer pipe 52, and is transferred to the confluence portion 57 by the rotation of the first spiral conveyor 58 arranged in the first horizontal transfer pipe 55, and is supplied to the developing device 23 through the third vertical transfer pipe 54 communicating with the confluence discharge port 57A. On the other hand, the toner discharged from the lower toner container 51 flows into the second horizontal transfer pipe 56 through the second vertical transfer pipe 53, and is transferred to the confluence portion 57 by the rotation of the second spiral conveyor 59 arranged in the second horizontal transfer pipe 56, and is supplied to the developing device 23 through the third vertical transfer pipe 54 communicating with the confluence discharge port 57A. Even when one of the upper toner container 50 and the lower toner container 51 becomes empty, the developing device 23 can be supplied with toner from the other container. Therefore, the frequency and time of stopping the image forming operation due to the replacement of the container can be reduced.

[0070] As described above, the first spiral conveyor 58 and the second spiral conveyor 59 are arranged in a V shape in which the region on the downstream side approaches the confluence portion 57 with respect to the upstream side, with the angle θ formed by the first horizontal rotation axis 58A and the second horizontal rotation axis 59A being an acute angle. Thereby, the toner conveyed by the first spiral conveyor 58 and the second spiral conveyor 59 can be effectively confluent at the confluence portion 57.

[0071] Refer to Figure 6, assume that in the arrangement direction (left - right direction) of multiple toner supply units 5, the intervals (developer device intervals) between adjacent developing devices 23 and the intervals (first container intervals) between upper toner containers 50 of adjacent toner supply units 5 are different. In this case, between adjacent toner supply units 5, the intervals PC1, PC2, PC3 between the first vertical tube axes 52A of the first vertical transfer tubes 52 communicating with the upper toner containers 50 and the intervals PD1, PD2, PD3 between the third vertical tube axes 54A of the third vertical transfer tubes 54 communicating with the developing devices 23 are different. In this case, regarding the positional relationship at the confluence 57 between the respective rotation axes 58A, 59A of the first screw conveyor 58 and the second screw conveyor 59 and the third vertical tube axis 54A, when the position of the third vertical tube axis 54A is set at the central position between the respective rotation axes 58A, 59A, the angle θ formed by the first screw conveyor 58 and the second screw conveyor 59 configured in a V - shape is different for each toner supply unit 5 according to the interval deviation between the developer device interval and the first container interval.

[0072] Therefore, in each toner supply unit 5 of the present embodiment, when viewed from above in the vertical direction looking at the confluence 57, the first axial distance L1 between the first horizontal rotation axis 58A and the third vertical tube axis 54A and the second axial distance L2 between the second horizontal rotation axis 59A and the third vertical tube axis 54A are set to take different values. That is, within the confluence 57, the position of the third vertical tube axis 54A is not at the central position between the first horizontal rotation axis 58A and the second horizontal rotation axis 59A, but is biased toward a certain rotation axis side. The difference between the first axial distance L1 and the second axial distance L2 is set according to the interval deviation between the developer device interval and the first container interval, and is set to a larger value as this interval deviation becomes larger. Thereby, the interval deviation between the developer device interval and the first container interval can be absorbed, and the angle θ formed by the first screw conveyor 58 and the second screw conveyor 59 configured in a V - shape can be made consistent among the multiple toner supply units 5. Therefore, the configuration of the conveyance drive unit 70 for driving the first screw conveyor 58 and the second screw conveyor 59, such as the first input gear 75 and the third transmission gear 79 composed of bevel gears, can be shared among the multiple toner supply units 5, and cost reduction can be achieved.

[0073] In addition, as described above, the length of the first vertical conveyance pipe 52 communicating with the upper toner container 50 is set to a value larger than the length of the second vertical conveyance pipe 53 communicating with the lower toner container 51. As the length of the vertical conveyance pipe becomes longer, the compressive force applied to the toner accumulated in the vertical conveyance pipe becomes larger, and a phenomenon may occur in which the fluidity of the toner decreases. When the toner in a state where the fluidity has decreased in the first vertical conveyance pipe 52 flows into the first horizontal conveyance pipe 55 and is conveyed by the first screw conveyor 58 to the confluence portion 57, it is assumed that the toner is not properly discharged from the confluence discharge port 57A to the third vertical conveyance pipe 54.

[0074] In view of such an assumption, the first axial distance L1 corresponding to the first screw conveyor 58 is set to a value smaller than the second axial distance L2. Thereby, it is possible to shorten the flow distance of the toner conveyed by the first screw conveyor 58 to the confluence portion 57 from the first screw conveyor 58 to the confluence discharge port 57A. Therefore, even when the fluidity of the toner in the first vertical conveyance pipe 52 decreases due to the tube length being set to be long, the toner can be effectively discharged from the confluence discharge port 57A to the third vertical conveyance pipe 54.

[0075] In addition, the first axial distance L1 is set to be equal to or less than the value obtained by adding the opening radius of the confluence discharge port 57A and the rotation radius of the first blade 584 provided on the first screw conveyor 58. Similarly, the second axial distance L2 is set to be equal to or less than the value obtained by adding the opening radius of the confluence discharge port 57A and the rotation radius of the second blade 594 provided on the second screw conveyor 59. Thereby, it is possible to reduce the frequency of the phenomenon in which the toner conveyed to the confluence portion 57 by the first screw conveyor 58 and the second screw conveyor 59 stays between each screw conveyor 58, 59 and the confluence discharge port 57A, and the toner can be effectively discharged from the confluence discharge port 57A to the third vertical conveyance pipe 54 through the respective blades 584, 594.

[0076] Further, the technical idea that the first axial distance L1 and the second axial distance L2 are different values and the first axial distance L1 is set to a value shorter than the second axial distance L2 is not limited to the application to the image forming apparatus 10 having four toner supply units 5 corresponding to four colors of toner. This technical idea can also be applied to a monochromatic image forming apparatus (such as a black-and-white machine) having one toner supply unit 5. When the above technical idea is applied to a monochromatic image forming apparatus, even when the fluidity of the toner in the first vertical conveyance pipe 52 decreases due to the tube length being set to be long, the above-described effect of being able to effectively discharge the toner from the confluence discharge port 57A to the third vertical conveyance pipe 54 is maintained.

[0077] Figure 9 This is a block diagram of the control unit 80 of the image forming apparatus 10. The image forming apparatus 10 includes a control unit 80 that controls each toner supply unit 5. The control unit 80 is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores control programs, a RAM (Random Access Memory) used as a work area of the CPU, and the like. In addition, the control unit 80 is electrically connected not only to the aforementioned motor 71 but also to a container drive unit 70C, a first conveyance detection sensor 81, a second conveyance detection sensor 82, a motor rotation detection sensor 83, and a display unit 84.

[0078] The display unit 84 is provided on an operation unit (not shown) of the image forming apparatus 10. The display unit 84 displays operation information, operation status information, and the like of the image forming apparatus 10.

[0079] The first conveyance detection sensor 81, the second conveyance detection sensor 82, and the motor rotation detection sensor 83 are sensors respectively provided on a plurality of toner supply units 5. The first conveyance detection sensor 81 is a sensor that detects the rotation of the first screw conveyor 58. The structure of the first conveyance detection sensor 81 is not particularly limited. For example, the first conveyance detection sensor 81 can be composed of a detected piece provided on the first shaft 581 of the first screw conveyor 58 and formed with a plurality of slits, and a PI sensor that detects detection light passing through the slits. In addition, the first conveyance detection sensor 81 can also be composed of an actuator provided on the first shaft 581 and a switch operated by the actuator.

[0080] The second conveyance detection sensor 82 is a sensor that detects the rotation of the second screw conveyor 59. The structure of the second conveyance detection sensor 82 is not particularly limited. For example, the second conveyance detection sensor 82 can be composed of a detected piece provided on the second shaft 591 of the second screw conveyor 59 and formed with a plurality of slits, and a PI sensor that detects detection light passing through the slits. In addition, the second conveyance detection sensor 82 can also be composed of an actuator provided on the second shaft 591 and a switch operated by the actuator.

[0081] The motor rotation detection sensor 83 is a sensor that detects the rotation of the motor 71. The structure of the motor rotation detection sensor 83 is not particularly limited. For example, the motor rotation detection sensor 83 can be composed of a detected piece provided on the worm wheel 72 connected to the motor 71 and formed with a plurality of slits, and a PI sensor that detects detection light passing through the slits. In addition, the motor rotation detection sensor 83 can also be composed of an actuator provided on the worm wheel 72 and a switch operated by the actuator, or can be a structure that applies a periodic load to the actuator to detect a change in the current supplied to the motor 71.

[0082] The control unit 80 executes the control program stored in the ROM through the CPU, and functions to drive the control unit 801, the consumption calculation unit 802, and the storage unit 803.

[0083] The storage unit 803 stores in advance various threshold information referred to by the drive control unit 801 and the consumption calculation unit 802, and arithmetic information such as constants used in arithmetic operations.

[0084] The drive control unit 801 controls the driving of the motor 71 and the container drive unit 70C. The drive control unit 801 switches between a first replenishment state in which toner is replenished from the upper toner container 50 to the developing device 23 and a second replenishment state in which toner is replenished from the lower toner container 51 to the developing device 23 according to a toner replenishment request from the developing device 23.

[0085] In the first replenishment state, the drive control unit 801 controls the container drive unit 70C to discharge toner from the upper toner container 50 through the first vertical transfer pipe 52, and rotates the motor 71 in the first rotation direction according to the replenishment request to rotate the first screw conveyor 58. At this time, the rotation of the first screw conveyor 58 is detected by the first transfer detection sensor 81, and the rotation of the motor 71 in the first rotation direction is detected by the motor rotation detection sensor 83.

[0086] On the other hand, in the second replenishment state, the drive control unit 801 controls the container drive unit 70C to discharge toner from the lower toner container 51 through the second vertical transfer pipe 53, and rotates the motor 71 in the second rotation direction according to the replenishment request to rotate the second screw conveyor 59. At this time, the rotation of the second screw conveyor 59 is detected by the second transfer detection sensor 82, and the rotation of the motor 71 in the second rotation direction is detected by the motor rotation detection sensor 83.

[0087] The consumption calculation unit 802 calculates the cumulative values of the rotation amounts (e.g., rotation time) of the first screw conveyor 58 and the second screw conveyor 59 based on the detection results of the first transfer detection sensor 81 and the second transfer detection sensor 82, respectively. In addition, the consumption calculation unit 802 calculates the cumulative values of the rotation amounts (e.g., rotation time) of the motor 71 when the first screw conveyor 58 and the second screw conveyor 59 are rotated for each screw conveyor based on the detection result of the motor rotation detection sensor 83. The consumption calculation unit 802 calculates the flow rates of the toner flowing in the first horizontal transfer pipe 55 and the second horizontal transfer pipe 56 based on the calculation results of the above respective rotation amounts, thereby calculating the consumption amounts of the toner in the upper toner container 50 and the lower toner container 51, respectively.

[0088] The flow rate of the toner in the first horizontal transfer pipe 55 and the second horizontal transfer pipe 56 is calculated based on the product of the cross-sectional area of each transfer pipe, the rotation speed (revolution speed) of each screw conveyor, and the pitch of the screw blades of the first main transfer blade 582 and the second main transfer blade 592. At this time, since the toner is replenished from the upper toner container 50 and the lower toner container 51 to the first vertical transfer pipe 52 and the second vertical transfer pipe 53 at any time, the first horizontal transfer pipe 55 and the second horizontal transfer pipe 56 are maintained in a state filled with the toner. Therefore, the flow rate of the toner is calculated with high precision by the above product. Then, the toner consumption of the upper toner container 50 or the lower toner container 51 is calculated by multiplying the flow rate of the toner in the first horizontal transfer pipe 55 or the second horizontal transfer pipe 56, which is calculated, by the cumulative value of the respective rotation amounts (rotation times). Information related to the toner consumption calculated by the consumption calculation unit 802 is displayed on the display unit 84.

[0089] In addition, when new upper toner container 50 and lower toner container 51 are respectively installed in the image forming apparatus 10, the consumption calculation unit 802 resets the cumulative value of the respective rotation amounts. In order to obtain information related to the installation of the new upper toner container 50 and lower toner container 51, the information of an RFID memory (not shown) provided in each container can be referred to. In addition, it can also be input by the user and the maintenance operator from an operation unit (not shown) of the image forming apparatus 10. Further, when the consumption of each toner container approaches the toner filling amount of the new toner container, the consumption calculation unit 802 causes the display unit 84 to display empty information of the toner container. As a result, the user can recognize that the toner container is approaching empty or has become empty. In addition, as described above, when one of the toner containers in the upper toner container 50 and the lower toner container 51 becomes empty, the drive control unit 801 switches the drive of the container drive unit 70C and the motor 71 so as to replenish the developing device 23 with toner from the other toner container.

[0090] Figure 10 FIG. is a view of the toner replenishing unit 5A according to a modified embodiment of the present invention as viewed from above. The toner replenishing unit applied to the image forming apparatus 10 is not limited to the above-described toner replenishing unit 5, and may also be Figure 10The toner supply unit 5A shown. In this case, the image forming apparatus 10 is configured to include a plurality (at least three) of toner supply units 5A provided corresponding to the plurality of image forming units 13 respectively. In the present modified embodiment, as the plurality of toner supply units 5A, there are provided a first toner supply unit 5AY corresponding to the first image forming unit 13Y, a second toner supply unit 5AC corresponding to the second image forming unit 13C, a third toner supply unit 5AM corresponding to the third image forming unit 13M, and a fourth toner supply unit 5ABK corresponding to the fourth image forming unit 13BK. The first to fourth toner supply units 5AY, 5AC, 5AM, 5ABK of the plurality of toner supply units 5A are arranged along the same arrangement direction (left - right direction) as the image forming units 13. The first to fourth toner supply units 5AY, 5AC, 5AM, 5ABK have the same structure except for the color of the toner used, and are sometimes collectively referred to as the toner supply unit 5A.

[0091] In the toner supply unit 5A, the positional relationship at the confluence portion 57 between the respective rotation shafts 58A, 59A of the first screw conveyor 58 and the second screw conveyor 59 and the third vertical tube axis 54A is different from that of the above - described toner supply unit 5. Specifically, in the toner supply unit 5A, when viewed from above in a plan view of the confluence portion 57 in the vertical direction, the first axial distance L1 between the first horizontal rotation shaft 58A and the third vertical tube axis 54A and the second axial distance L2 between the second horizontal rotation shaft 59A and the third vertical tube axis 54A are set to the same value. That is, within the confluence portion 57, the position of the third vertical tube axis 54A is set at the central position between the first horizontal rotation shaft 58A and the second horizontal rotation shaft 59A. In this configuration, it is assumed that in the arrangement direction (left - right direction) of the plurality of toner supply units 5A, the interval between adjacent developing devices 23 (developing device interval) is different from the interval between the upper toner containers 50 of adjacent toner supply units 5A (first container interval). In this case, the angle θ formed by the first screw conveyor 58 and the second screw conveyor 59 configured in a V - shape is the same for each toner supply unit 5A according to the interval deviation between the developing device interval and the first container interval.

[0092] In the present modified embodiment, the method for making the angle θ formed by the first screw conveyor 58 and the second screw conveyor 59 configured in a V - shape consistent among the plurality of toner supply units 5A is roughly divided into a first method and a second method. Hereinafter, the above - described first method and second method will be described in sequence.

[0093] First, in the first mode of this modified embodiment, the intervals in the arrangement direction (left - right direction) between the first vertical transfer pipes 52 among adjacent toner supply units 5A and the intervals in the arrangement direction (left - right direction) between the second vertical transfer pipes 53 are set to the same value. Refer to Figure 10 Specifically, the interval PC1 between the first vertical transfer pipes 52 in the first toner supply unit 5AY and the second toner supply unit 5AC, the interval PC2 between the first vertical transfer pipes 52 in the second toner supply unit 5AC and the third toner supply unit 5AM, and the interval PC3 between the first vertical transfer pipes 52 in the third toner supply unit 5AM and the fourth toner supply unit 5ABK are set to the same value. Therefore, the intervals in the arrangement direction (the first container pitch) between the upper toner containers 50 among adjacent toner supply units 5A are the same, and the intervals in the arrangement direction (the second container pitch) between the lower toner containers 51 are the same. In other words, the plurality of upper toner containers 50 are arranged at equal intervals along the arrangement direction, and the plurality of lower toner containers 51 are arranged at equal intervals along the arrangement direction.

[0094] In addition, the intervals in the arrangement direction (left - right direction) between the third vertical transfer pipes 54 among adjacent toner supply units 5A are set to the same value. Refer to Figure 10 Specifically, the interval PD1 between the third vertical transfer pipes 54 in the first toner supply unit 5AY and the second toner supply unit 5AC, the interval PD2 between the third vertical transfer pipes 54 in the second toner supply unit 5AC and the third toner supply unit 5AM, and the interval PD3 between the third vertical transfer pipes 54 in the third toner supply unit 5AM and the fourth toner supply unit 5ABK are set to the same value. Therefore, the intervals in the arrangement direction (developer unit pitch) between the adjacent developing devices 23 for each color are the same. In other words, the developing devices 23 for each color are arranged at equal intervals along the arrangement direction.

[0095] Furthermore, in each toner supply unit 5A, the first vertical conveyance pipe 52 and the second vertical conveyance pipe 53 are arranged at the same position in the front-back direction along the drum shaft 20A. Accordingly, the upper toner container 50 communicating with the first vertical conveyance pipe 52 and the lower toner container 51 communicating with the second vertical conveyance pipe 53 are arranged at the same position in the front-back direction along the drum shaft 20A. In this state, in the plurality of toner supply units 5A, the first vertical conveyance pipe 52 or the third vertical conveyance pipe 54 is arranged at mutually different positions in the front-back direction along the drum shaft 20A. At this time, in the case where the first vertical conveyance pipes 52 are arranged at mutually different positions in the front-back direction, the third vertical conveyance pipes 54 are arranged at the same position in the front-back direction. In addition, in the case where the third vertical conveyance pipes 54 are arranged at mutually different positions in the front-back direction, the first vertical conveyance pipes 52 are arranged at the same position in the front-back direction.

[0096] The position offset amount of each of the first vertical conveyance pipes 52 or each of the third vertical conveyance pipes 54 in the front-back direction is set according to the pitch deviation between the developing device pitch and the first container pitch, and is set to a large value as the pitch deviation becomes larger. Thereby, the pitch deviation between the developing device pitch and the first container pitch can be absorbed, and the angle θ formed by the first spiral conveyor 58 and the second spiral conveyor 59 configured in a V shape can be made consistent in the plurality of toner supply units 5A. Accordingly, the configuration of the conveyance drive unit 70 for driving the first spiral conveyor 58 and the second spiral conveyor 59, such as the first input gear 75 and the third transmission gear 79 formed of bevel gears, can be shared in the plurality of toner supply units 5A, and cost reduction can be achieved.

[0097] Next, in the second mode of the present modified embodiment, in each toner supply unit 5A, the first vertical conveyance pipe 52 and the second vertical conveyance pipe 53 are arranged at the same position in the front-back direction along the drum shaft 20A. Accordingly, the upper toner container 50 communicating with the first vertical conveyance pipe 52 and the lower toner container 51 communicating with the second vertical conveyance pipe 53 are arranged at the same position in the front-back direction along the drum shaft 20A. Furthermore, in the plurality of toner supply units 5A, each of the first vertical conveyance pipes 52 and each of the second vertical conveyance pipes 53 are arranged at the same position in the front-back direction along the drum shaft 20A. That is, all of the first vertical conveyance pipes 52 and the second vertical conveyance pipes 53 provided in each of the plurality of toner supply units 5A are arranged at the same position in the front-back direction along the drum shaft 20A. Accordingly, all of the upper toner containers 50 and the lower toner containers 51 provided in each of the plurality of toner supply units 5A are arranged at the same position in the front-back direction along the drum shaft 20A.

[0098] Further, between adjacent toner supply units 5A, the intervals in the arrangement direction (left - right direction) of the first vertical conveyance pipes 52 with respect to each other or the intervals in the arrangement direction (left - right direction) of the third vertical conveyance pipes 54 with respect to each other are set to different values. At this time, when the intervals in the arrangement direction of adjacent first vertical conveyance pipes 52 with respect to each other are set to different values, the intervals in the arrangement direction of adjacent third vertical conveyance pipes 54 with respect to each other are set to the same value. Further, when the intervals in the arrangement direction of adjacent third vertical conveyance pipes 54 with respect to each other are set to different values, the intervals in the arrangement direction of adjacent first vertical conveyance pipes 52 with respect to each other are set to the same value.

[0099] Refer to Figure 10 Specifically, the interval PC1 between the first vertical conveyance pipes 52 with respect to each other in the first toner supply unit 5AY and the second toner supply unit 5AC, the interval PC2 between the first vertical conveyance pipes 52 with respect to each other in the second toner supply unit 5AC and the third toner supply unit 5AM, and the interval PC3 between the first vertical conveyance pipes 52 with respect to each other in the third toner supply unit 5AM and the fourth toner supply unit 5ABK are set to different values. In this case, the intervals (first container intervals) between the upper toner containers 50 with respect to each other between adjacent toner supply units 5A are different in the arrangement direction, and the intervals (second container intervals) between the lower toner containers 51 with respect to each other are different in the arrangement direction. Alternatively, the interval PD1 between the third vertical conveyance pipes 54 with respect to each other in the first toner supply unit 5AY and the second toner supply unit 5AC, the interval PD2 between the third vertical conveyance pipes 54 with respect to each other in the second toner supply unit 5AC and the third toner supply unit 5AM, and the interval PD3 between the third vertical conveyance pipes 54 with respect to each other in the third toner supply unit 5AM and the fourth toner supply unit 5ABK are set to different values. In this case, the intervals (developer device intervals) between adjacent developing devices 23 for each color are different in the arrangement direction.

[0100] The offset amount in the arrangement direction of the interval between adjacent first vertical conveyance pipes 52 with respect to each other or the interval between adjacent third vertical conveyance pipes 54 with respect to each other is set according to the interval deviation between the developer device interval and the first container interval, and is set to a large value as this interval deviation becomes larger. Thereby, the interval deviation between the developer device interval and the first container interval can be absorbed, and the angle θ formed by the first spiral conveyor 58 and the second spiral conveyor 59 configured in a V - shape can be made consistent in the plurality of toner supply units 5A. Therefore, the configuration of the conveyance drive unit 70 for driving the first spiral conveyor 58 and the second spiral conveyor 59, for example, the first input gear 75 and the third transmission gear 79 formed of bevel gears, can be shared in the plurality of toner supply units 5A, and cost reduction can be achieved.

[0101] As described above, the image forming apparatus 10 according to one embodiment of the present invention has been described in detail. With such a configuration, an image forming apparatus can be provided in which, in each toner supply unit 5, the toner conveyed by the first screw conveyor 58 and the second screw conveyor 59 can be effectively merged at the merging portion 57, and the conveyance drive unit 70 that drives each of the screw conveyors 58 and 59 can be shared among a plurality of toner supply units 5. In addition, the present invention is not limited thereto. For example, the present invention may adopt the following modified embodiments.

[0102] In the above-described embodiment, the method of conveying the toner inside the upper toner container 50 and the lower toner container 51 by rotating the main body portion of the container has been described. However, the toner container may also include a rotatable toner conveying member such as a screw inside.

[0103] In addition, the toner replenishment request from the developing device 23 that the drive control unit 801 refers to in order to discharge the toner from the upper toner container 50 and the lower toner container 51 is not limited to the above-described method. The toner replenishment for the developing device 23 may also be determined based on other information such as the image information in the image forming apparatus 10 and the density information of the patch image on the intermediate transfer belt 141 of the intermediate transfer unit 14.

Claims

1. An image forming apparatus, characterized in that, Comprising: A plurality of image forming units, each having a photosensitive drum rotatable about a drum axis extending horizontally and a developing device for supplying toner to the photosensitive drum, the plurality of image forming units being arranged along an arrangement direction horizontally orthogonal to the drum axis; And A plurality of toner replenishing units, provided corresponding to the plurality of image forming units respectively, for replenishing toner to the developing device, Each of the plurality of toner replenishing units comprising: A first container and a second container, capable of storing toner therein and discharging toner; A first vertical conveying pipe, formed in a cylindrical shape having a peripheral wall surrounding a first vertical pipe axis extending vertically downward from the first container, for guiding the toner discharged from the first container vertically downward along the first vertical pipe axis; A second vertical conveying pipe, formed in a cylindrical shape having a peripheral wall surrounding a second vertical pipe axis extending vertically downward from the second container, for guiding the toner discharged from the second container vertically downward along the second vertical pipe axis; A first horizontal conveying pipe, formed in a cylindrical shape extending along a first horizontal direction intersecting the drum axis and the arrangement direction, connected to the lower end of the first vertical conveying pipe, and having a first inlet for toner to flow in; A second horizontal conveying pipe, formed in a cylindrical shape extending along a second horizontal direction at an acute angle with respect to the first horizontal direction, connected to the lower end of the second vertical conveying pipe, and having a second inlet for toner to flow in; A first conveying member, arranged in the first horizontal conveying pipe so as to be rotatable about a first horizontal rotation axis along the first horizontal direction, and conveying the toner flowing into the first horizontal conveying pipe through the first inlet to the downstream side by rotation; A second conveying member, arranged in the second horizontal conveying pipe so as to be rotatable about a second horizontal rotation axis along the second horizontal direction, and conveying the toner flowing into the second horizontal conveying pipe through the second inlet to the downstream side by rotation; A confluence portion, communicating with the downstream side portions of the first horizontal conveying pipe and the second horizontal conveying pipe respectively, internally receiving the toner conveyed by the first conveying member and the second conveying member, and having a confluence discharge port for discharging the received toner; A third vertical conveying pipe, formed in a cylindrical shape having a peripheral wall surrounding a third vertical pipe axis extending vertically downward from the confluence discharge port, for guiding the toner discharged from the confluence portion through the confluence discharge port vertically downward along the third vertical pipe axis toward the developing device; and A conveying driving portion, generating a driving force for rotating the first conveying member and the second conveying member, In a plan view of observing the confluence portion from the vertical direction, The confluence discharge port is arranged between the first horizontal rotation axis and the second horizontal rotation axis, A first axial distance between the first horizontal rotation axis and the third vertical pipe axis and a second axial distance between the second horizontal rotation axis and the third vertical pipe axis are set to take different values from each other.

2. The image forming apparatus according to claim 1, wherein The first container is above the second container and is arranged in a manner that it overlaps a part of the second container in a plan view observed from the vertical direction. The length of the first vertical transfer pipe along the first vertical pipe axis is set to a value larger than the length of the second vertical transfer pipe along the second vertical pipe axis. The first inter-axis distance is set to a value smaller than the second inter-axis distance.

3. The image forming apparatus according to claim 1, wherein The first transfer member has: A first shaft, arranged on the first horizontal rotation axis and rotated by the driving force of the transfer driving unit; A first transfer blade, arranged on the first shaft and rotated along with the rotation of the first shaft, thereby transferring the toner to the downstream side; and A first squeegee, arranged inside the confluence part on the downstream side of the first transfer blade on the first shaft and rotated along with the rotation of the first shaft, thereby sending the toner transferred from the first transfer blade to the confluence discharge port. The second transfer member has: A second shaft, arranged on the second horizontal rotation axis and rotated by the driving force of the transfer driving unit; A second transfer blade, arranged on the second shaft and rotated along with the rotation of the second shaft, thereby transferring the toner to the downstream side; And A second squeegee, arranged inside the confluence part on the downstream side of the second transfer blade on the second shaft and rotated along with the rotation of the second shaft, thereby sending the toner transferred from the second transfer blade to the confluence discharge port. The first inter-axis distance is set to a value equal to or less than the value obtained by adding the opening radius of the confluence discharge port and the rotation radius of the first squeegee. The second inter-axis distance is set to a value equal to or less than the value obtained by adding the opening radius of the confluence discharge port and the rotation radius of the second squeegee.

4. The image forming apparatus according to claim 1, wherein The transfer driving unit has: A motor capable of rotating in a first rotation direction and a second rotation direction opposite to the first rotation direction; and A swing gear capable of swinging between a first position and a second position according to the rotation direction of the motor, allowing the rotation of the first transfer member at the first position and allowing the rotation of the second transfer member at the second position.

5. The image forming apparatus according to claim 1, wherein The transfer driving unit includes: A motor capable of rotating in a first rotation direction and a second rotation direction opposite to the first rotation direction; A first one-way clutch that allows the rotation of the first transfer member when the motor rotates in the first rotation direction, and on the other hand, restricts the rotation of the first transfer member when the motor rotates in the second rotation direction; and A second one-way clutch that allows the rotation of the second transfer member when the motor rotates in the second rotation direction, and on the other hand, restricts the rotation of the second transfer member when the motor rotates in the first rotation direction.

6. The image forming apparatus according to claim 4, wherein Each toner supply unit further includes: A first conveyance detection sensor that detects the rotation of the first conveyance member; and A second conveyance detection sensor that detects the rotation of the second conveyance member.

7. The image forming apparatus according to claim 4, wherein each of the toner replenishing units further includes a motor rotation detection sensor that detects the rotation of the motor.

8. An image forming apparatus, characterized in that, Comprising: At least three image forming units, each having a photosensitive drum that can rotate around a drum axis extending horizontally, and a developing device that supplies toner to the photosensitive drum, and the at least three image forming units are arranged along an arrangement direction that is horizontally orthogonal to the drum axis; and At least three toner replenishing units, which are respectively provided corresponding to the at least three image forming units, and replenish toner to the developing device, The at least three toner replenishing units each include: A first container and a second container that can store toner therein and discharge toner; A first vertical conveyance pipe, formed in a cylindrical shape having a peripheral wall that surrounds a first vertical pipe axis extending vertically downward from the first container, and guides the toner discharged from the first container vertically downward along the first vertical pipe axis; A second vertical conveyance pipe, formed in a cylindrical shape having a peripheral wall that surrounds a second vertical pipe axis extending vertically downward from the second container, and guides the toner discharged from the second container vertically downward along the second vertical pipe axis; A first horizontal conveyance pipe, formed in a cylindrical shape extending along a first horizontal direction that intersects the drum axis and the arrangement direction, connected to the lower end of the first vertical conveyance pipe, and having a first inlet through which toner flows in; A second horizontal conveyance pipe, formed in a cylindrical shape extending along a second horizontal direction that forms an acute angle with respect to the first horizontal direction, connected to the lower end of the second vertical conveyance pipe, and having a second inlet through which toner flows in; A first conveyance member, disposed in the first horizontal conveyance pipe so as to be rotatable around a first horizontal rotation axis along the first horizontal direction, and conveys the toner flowing into the first horizontal conveyance pipe through the first inlet to the downstream side by rotation; A second conveyance member, disposed in the second horizontal conveyance pipe so as to be rotatable around a second horizontal rotation axis along the second horizontal direction, and conveys the toner flowing into the second horizontal conveyance pipe through the second inlet to the downstream side by rotation; A confluence portion, communicating with the downstream side portions of the first horizontal conveyance pipe and the second horizontal conveyance pipe respectively, internally receiving the toner conveyed by the first conveyance member and the second conveyance member, and having a confluence discharge port for discharging the received toner; A third vertical conveyance pipe, formed in a cylindrical shape having a peripheral wall that surrounds a third vertical pipe axis extending vertically downward from the confluence discharge port, and guides the toner discharged from the confluence portion through the confluence discharge port vertically downward along the third vertical pipe axis toward the developing device; and A conveyance driving unit that generates a driving force for rotating the first conveyance member and the second conveyance member, When looking down at the confluence portion from the vertical direction, The confluent discharge port is disposed between the first horizontal rotation axis and the second horizontal rotation axis, The first axial distance between the first horizontal rotation axis and the third vertical pipe axis and the second axial distance between the second horizontal rotation axis and the third vertical pipe axis are set to the same value, The intervals in the arrangement direction between the adjacent first vertical conveying pipes or the intervals in the arrangement direction between the third vertical conveying pipes among the at least three toner supply units are set to different values.

Images