Developer conveyance device including spiral coil, and image forming device including the developer conveyance device

Abstract

In a developer conveyance device, a spiral screw is arranged inside a spiral coil such that the spiral coil and the spiral screw are both rotated. Accompanied by rotation of the spiral coil, even if waste toner tries to pass through the spiral coil and move in a vertical direction, movement of the waste toner in the vertical direction is blocked by the spiral screw, such that the waste toner is conveyed by the spiral screw. Since the waste toner hardly passes through the spiral coil in the vertical direction, the waste toner is also conveyed by the spiral coil.

Claims

1. A developer conveyance device, comprising: a spiral coil provided in a conveyance path of a developer and configured to convey the developer by rotating; a shaft member passing through and attached to an end portion of the spiral coil and rotatably supporting the end portion of the spiral coil; and a spiral screw provided on an outer periphery of the shaft member and arranged inside the spiral coil; wherein the spiral coil has a pitch at the end portion that is narrower than a pitch at a center of the spiral coil such that a distance between centers of adjacent coils of the spiral coil is smaller at the end portion than a distance between centers of adjacent coils of the spiral coil at the center.

2. The developer conveyance device according to claim 1, wherein the conveyance path includes a tubular member through which the spiral coil is passed, and the tubular member is provided with an opening in a portion where there is the shaft member.

3. The developer conveyance device according to claim 2, wherein the spiral screw is extended in a direction of conveyance of the developer relative to the opening of the tubular member.

4. The developer conveyance device according to claim 2, wherein a pitch of the spiral coil at the opening is less than a pitch of the spiral screw.

5. An image forming device comprising the developer conveyance device according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a sectional view illustrating an image forming device, to which a developer conveyance device of a first preferred embodiment of the present invention is applied, viewed from a front side.

(2) FIG. 2 is a view schematically illustrating the developer conveyance device of the first preferred embodiment of the present invention and a waste toner bottle arranged in the image forming device of FIG. 1 viewed from a rear side of the image forming device.

(3) FIG. 3 is an enlarged perspective view illustrating a waste toner receiving unit, a conveyance hose, and the like in the developer conveyance device of the first preferred embodiment of the present invention.

(4) FIG. 4 is a perspective view illustrating the partially broken waste toner receiving unit.

(5) FIG. 5 is a perspective view illustrating a joint unit of the waste toner receiving unit.

(6) FIG. 6 is a perspective view illustrating the partially broken waste toner receiving unit, the conveyance hose, and the like.

(7) FIGS. 7A and 7B are perspective views each illustrating an area near one end portion of a spiral coil and a shaft member.

(8) FIG. 8 is a perspective view illustrating a waste toner recovery unit and the conveyance hose in the developer conveyance device of the first preferred embodiment of the present invention.

(9) FIG. 9 is a planar view illustrating the waste toner recovery unit.

(10) FIG. 10 is an underside view illustrating the waste toner recovery unit.

(11) FIG. 11 is a side view illustrating an area around the other end portion of the spiral coil.

(12) FIG. 12 is a sectional view schematically illustrating a developer conveyance device according to a second preferred embodiment of the present invention.

(13) FIG. 13 is a perspective view illustrating a screw member in the developer conveyance device of the second preferred embodiment of the present invention.

(14) FIG. 14 is a sectional view illustrating an image forming device, to which a developer conveyance device of a third preferred embodiment of the present invention is applied, viewed from the front side.

(15) FIG. 15 is a rear side view schematically illustrating the developer conveyance device and the waste toner bottle of the third preferred embodiment of the present invention arranged in the image forming device of FIG. 14 viewed from a rear side of the image forming device.

(16) FIG. 16 is a view schematically illustrating the developer conveyance device of the third preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(17) Hereinafter, preferred embodiments of the present invention are described based on the drawings.

(18) First Preferred Embodiment

(19) FIG. 1 is a sectional view illustrating an image forming device, to which a developer conveyance device of a first preferred embodiment of the present invention is applied, viewed from a front side. An image forming device 1 preferably is configured by combining a printing unit 2, an image reading device 3, an original conveyance device 4, a post-processing device 5, a paper supply device 6, a double-sided conveyance device 7, and the like.

(20) The printing unit 2 preferably is configured by arranging a charging device 17, an optical scanning device 18, a developing device 12, a transfer device 13, a cleaning device 14, a discharging lamp device (not illustrated), and the like around a photoreceptor drum 15. Furthermore, the photoreceptor drum 15, the charging device 17, the developing device 12, the transfer device 13, the cleaning device 14, and the discharging lamp device are preferably incorporated into one cartridge 19 as a unit, such that replacement by the cartridge 19 is possible.

(21) In this printing unit 2, a surface of the photoreceptor drum 15 is uniformly charged by the charging device 17. The surface of the photoreceptor drum 15 is scanned by the optical scanning device 18, and an electrostatic latent image is written on the surface of the photoreceptor drum 15. Then, toner (developer) is applied to the electrostatic latent image on the surface of the photoreceptor drum 15 by the developing device 12. The electrostatic latent image on the surface of the photoreceptor drum 15 is developed to form a toner image, and the toner image is transferred from the surface of the photoreceptor drum 15 to recording paper by the transfer device 13. Further, the toner remaining on the surface of the photoreceptor drum 15 is removed by the cleaning device 14. The surface of the photoreceptor drum 15 is cleaned, and an electric charge on the surface of the photoreceptor drum 15 is removed by the discharging lamp device (not illustrated).

(22) Furthermore, a paper supply unit 16 is arranged below the printing unit 2, and further below the paper supply unit 16, the paper supply device 6 is provided. The paper supply device 6 preferably includes three paper supply units 6a, 6b, and 6c, for example. A plurality of recording paper is stacked and housed in each of the paper supply units 16, 6a, 6b, and 6c. The recording paper is drawn out one sheet by one sheet from any of the paper supply units 16, 6a, 6b, and 6c and is supplied to the printing unit 2. The recording paper is conveyed to a nip zone between the photoreceptor drum 15 and the transfer device 13 where the toner image formed on the surface of the photoreceptor drum 15 is transferred thereon. Here, during operation of the image forming device 1, any of the paper supply units 16, 6a, 6b, and 6c in which the recording paper of a desired size is housed is selectively operated. The recording paper is conveyed and supplied to the nip zone between the photoreceptor drum 15 and the transfer device 13, and the toner image is transferred on this recording paper.

(23) Further, a fixing device 21 is arranged above the transfer device 13 of the printing unit 2, and the recording paper on which the toner image has been transferred is conveyed to the fixing device 21. The fixing device 21 heats and pressurizes the recording paper, fixes the toner image on the recording paper, and discharges the recording paper.

(24) Subsequently, the recording paper is conveyed from the fixing device 21 to a relay conveyance device 8. In the relay conveyance device 8, the recording paper is introduced through a paper ejection roller 23, and by switching a switching gate 24, the recording paper is relayed and conveyed to the post-processing device 5 or is discharged to a discharge tray 25.

(25) In the post-processing device 5, when the recording paper is introduced through a feed-in roller 26, by switching a switching gate 27, the recording paper is discharged without being post-processed to an upper deck paper ejection tray 28 or the recording paper is discharged to a lower deck paper ejection tray 29 after being post-processed.

(26) The double-sided conveyance device 7 turns over the recording paper from a front surface to a back surface thereof when recording the toner image on both surfaces of the recording paper. Here, the toner image is recorded on the front surface of the recording paper, and when the recording paper is conveyed to the paper ejection roller 23, in the middle of conveyance of the recording paper by the paper ejection roller 23, the paper ejection roller 23 temporarily stops. The paper ejection roller 23 is reversely rotated, and the recording paper is guided to the double-sided conveyance device 7 by switching a gate 22. The recording paper is guided again to the printing unit 2 through the double-sided conveyance device 7, and the recording paper is turned over from the front surface to the back surface. The toner image is recorded on the back surface of the recording paper by the printing unit 2, and the recording paper is conveyed to the relay conveyance device 8 through the paper ejection roller 23.

(27) On the other hand, reading of an original by the image reading device 3 is performed either in an automatic reading mode or a manual reading mode. In the automatic reading mode, the original is drawn out from an original set tray 36 by the original conveyance device 4. It is conveyed on an original placement table 35 and is discharged to an original discharge tray 37. In the image reading device 3, a first scanning unit 31 and a second scanning unit 32 are each positioned to a specified position. The original conveyed on the original placement table 35 is exposed by a light source of the first scanning unit 31, and by a mirror of each of the first scanning unit 31 and the second scanning unit 32, reflection light from the original is guided to a photoelectric conversion element 34 through an image forming lens 33. An image on the original is read by the photoelectric conversion element 34, and image data representing the image on the original is output.

(28) In the manual reading mode, the original conveyance device 4 is rotary moved upward centering on a spindle on an end portion on a rear side of the original conveyance device 4. The original placement table 35 is opened, and the original is placed on the original placement table 35. In the image reading device 3, while alternately moving the first scanning unit 31 and the second scanning unit 32 at a predetermined speed relationship, the original on the original placement table 35 is exposed by the first scanning unit 31 and the second scanning unit 32. The reflection light from the original is guided to the photoelectric conversion element 34 through the image forming lens 33. The image on the original is read by the photoelectric conversion element 34, and the image data representing the image on the original is output.

(29) The image data, after being image processed, is given to the optical scanning device 18 of the printing unit 2, and an electrostatic latent image corresponding to the image data is written on the surface of the photoreceptor drum 15 by the optical scanning device 18. Then, as described above, the electrostatic latent image on the surface of the photoreceptor drum 15 is developed. The toner image is transferred from the surface of the photoreceptor drum 15 to the recording paper, and the toner image on the recording paper is fixed.

(30) In the printing unit 2 of the image forming device 1, the electrostatic latent image on the surface of the photoreceptor drum 15 is developed by the developing device 12 and becomes the toner image. After the toner image has been transferred from the surface of the photoreceptor drum 15 to the recording paper by the transfer device 13, the toner remaining on the surface of the photoreceptor drum 15 is removed by the cleaning device 14. Then, the removed toner is conveyed to a waste toner bottle as a waste toner and is recovered.

(31) The developer conveyance device of the first preferred embodiment performs conveyance of the waste toner from the cleaning device 14 to the waste toner bottle. Next, the developer conveyance device of the first preferred embodiment is described in detail.

(32) FIG. 2 is a view schematically illustrating a developer conveyance device 41 and a waste toner bottle 42 of the first preferred embodiment arranged in the image forming device 1 viewed from a rear side of the image forming device 1. Note, however, that in FIG. 2, a portion or element providing the same function as a portion or element in FIG. 1 is denoted with the same reference numeral. FIG. 1 is a view in which the developer conveyance device 41 and the waste toner bottle 42 are omitted.

(33) As illustrated in FIG. 2, the waste toner bottle 42 is detachably arranged and is placed on a bottom of the paper supply device 6. The developer conveyance device 41 is provided with a waste toner receiving unit 43 detachably installed to the cartridge 19, a waste toner recovery unit 44 placed on a shelf 1a inside the image forming device 1 and arranged to an upper portion of the waste toner bottle 42, a conveyance hose 45 connecting the waste toner receiving unit 43 to the waste toner recovery unit 44, and the like. The developer conveyance device 41 receives the waste toner from the cleaning device 14 in the cartridge 19 to the waste toner receiving unit 43, conveys the waste toner from the waste toner receiving unit 43 to the waste toner recovery unit 44 through the conveyance hose 45, and further discharges the waste toner from the waste toner recovery unit 44 to the waste toner bottle 42, such that the waste toner is housed and recovered in the waste toner bottle 42.

(34) FIG. 3 is an enlarged perspective view illustrating the cartridge 19, the waste toner receiving unit 43, and the conveyance hose 45. FIG. 4 is a perspective view illustrating the partially broken waste toner receiving unit 43, and FIG. 5 is a perspective view illustrating a joint unit 46 of the waste toner receiving unit 43. Further, FIG. 6 is a perspective view illustrating the partially broken waste toner receiving unit 43, the conveyance hose 45, and the like.

(35) As illustrated in FIGS. 3 to 6, the waste toner receiving unit 43 preferably includes a main body includes a cylindrical cover 43a, a semi-cylindrical portion 43b, and each of flat plate portions 43c provided on both sides of the semi-cylindrical portion 43b; and the joint unit 46 including a substantially lower portion of the waste toner receiving unit 43. The main body preferably is a molded article of synthetic resin having sufficient rigidity. The waste toner receiving unit 43 is detachably installed to the cartridge 19, and the cylindrical cover 43a is connected to the cleaning device 14 of the cartridge 19. In the cleaning device 14, for example, a blade (not illustrated) is slidingly contacted to the surface of the photoreceptor drum 15, and the toner remaining on the surface of the photoreceptor drum 15 is scraped off by the blade. The waste toner that has been scraped off is conveyed by a screw extending in a shaft direction of the photoreceptor drum 15 to inside of the cylindrical cover 43a of the waste toner receiving unit 43 and is discharged. Thus, the waste toner that has been removed and conveyed from the surface of the photoreceptor drum 15 by the cleaning device 14 is discharged to the inside of the cylindrical cover 43a of the waste toner receiving unit 43.

(36) A lower half of the semi-cylindrical portion 43b of the waste toner receiving unit 43 is opened, and the joint unit 46 is installed below the semi-cylindrical portion 43b. This joint unit 46 includes a semi-cylindrical portion 46a, a cylindrical portion 46b continuously formed with the semi-cylindrical portion 46a, and each of flat plate portions 46c provided on both sides of the semi-cylindrical portion 46a and the cylindrical portion 46b. An upper half of the semi-cylindrical portion 46a is opened.

(37) Here, one end 45a of the conveyance hose 45 is inserted inside the semi-cylindrical portion 46a of the joint unit 46, and each of the flat plate portions 46c of the joint unit 46 is overlapped with and fixed to each of the flat plate portions 43c on both sides of the semi-cylindrical portion 43b. Inside a cylinder including the semi-cylindrical portion 46a on a lower side and the semi-cylindrical portion 43b on an upper side, the one end 45a of the conveyance hose 45 is fitted and supported.

(38) In this state, an opening 46d in an upper portion of the cylindrical portion 46b of the joint unit 46 is positioned below the cylindrical cover 43a. Accordingly, the waste toner discharged from the cleaning device 14 to the inside of the cylindrical cover 43a of the waste toner receiving unit 43 is naturally dropped to the opening 46d of the cylindrical portion 46b of the joint unit 46 inside the cylindrical cover 43a.

(39) One spiral coil 51 is rotatably inserted inside the conveyance hose 45, and the spiral coil 51 extends from the waste toner receiving unit 43 to the waste toner recovery unit 44. The conveyance hose 45 is a tubular body preferably made of, for example, a flexible synthetic resin, and the spiral coil 51 is preferably made of, for example, a spirally molded metal thin belt. Thus, as illustrated in FIG. 2, any portion of the conveyance hose 45 and the spiral coil 51 is capable of being flexibly curved and disposed between the waste toner receiving unit 43 and the waste toner recovery unit 44.

(40) A shaft member 52 is inserted inside one end portion 51a of the spiral coil 51, and the one end portion 51a of the spiral coil 51 is coupled and locked to the shaft member 52.

(41) FIGS. 7A and 7B are perspective views each illustrating an area near one end portion of the spiral coil 51 and the shaft member 52. As illustrated in FIG. 7A, the spiral coil 51 preferably includes the spirally molded metal thin belt, and a pitch P1a at the one end portion 51a of the spiral coil 51 preferably is narrower than a pitch P1 near the center of the spiral coil 51. The pitch P1 is maintained to be constant entirely or substantially entirely excluding both end portions of the spiral coil 51. In the one end portion 51a of the spiral coil 51, an engagement portion 51b configured by bending an end piece of the spiral coil 51 at a right angle or a substantially right angle is provided.

(42) As illustrated in FIG. 7B, the shaft member 52 preferably is made of a synthetic resin (for example, ABS) molded article having sufficient rigidity, and includes a cylindrical shaft 52a; a spiral screw 52b provided on an outer periphery of the cylindrical shaft 52a; two projections 52c and 52d each installed in a protruding manner on the outer periphery of the cylindrical shaft 52a in an opposite direction from each other at a half distance of the pitch P1a; a fitting recess 52e provided separately from the projection 52d; a round plate 52f; and an shaft end portion 52g. A direction of a spiral of the spiral screw 52b of the shaft member 52 is the same as a direction of a spiral of the spiral coil 51. A pitch P2 of the spiral screw 52b preferably is set to be sufficiently longer than the pitch P1a of the one end portion 51a of the spiral coil 51. Further, the spiral screw 52b is extended to an area near the conveyance hose 45 relative to the opening 46d of the cylindrical portion 46b (toner conveyance direction) and is outside of an area of the opening 46d.

(43) As illustrated in FIGS. 4 and 6, the shaft member 52 is inserted into the one end portion 51a of the spiral coil 51. The spiral coil 51 passes through each of the projections 52c and 52d of the shaft member 52, and the engagement portion 51b of the spiral coil 51 is fitted into the fitting recess 52e of the shaft member 52. Thus, the one end portion 51a of the spiral coil 51 is coupled and locked to the shaft member 52, and the spiral screw 52b of the shaft member 52 is arranged inside of the one end portion 51a of the spiral coil 51.

(44) A bearing portion 53 is fitted to an end portion of the cylindrical portion 46b of the joint unit 46. The shaft end portion 52g of the shaft member 52 is inserted into a hole in the middle of the bearing portion 53, and outside of the bearing portion 53, a retaining snap ring (not illustrated) is fitted to a groove 52h of the shaft end portion 52g. Thus, the shaft member 52 is pivotally supported, and the one end portion 51a of the spiral coil 51 is rotatably supported.

(45) In this way, the one end portion 51a of the spiral coil 51 is coupled and locked to the shaft member 52, such that the spiral coil 51 and the shaft member 52 are integrally rotated inside the conveyance hose 45 and the cylindrical portion 46b of the joint unit 46.

(46) On the other hand, the waste toner recovery unit 44 is configured as follows. FIG. 8 is a perspective view illustrating the waste toner recovery unit 44 and the conveyance hose 45. FIGS. 9 and 10 are a planar view and an underside view illustrating the waste toner recovery unit 44. Further, FIG. 11 is a side view illustrating around another end portion 51c of the spiral coil 51.

(47) As illustrated in FIGS. 8 to 11, the waste toner recovery unit 44 preferably includes a rectangular or substantially rectangular main plate 61; a joint unit 62 coupled and locked to the other end portion 51c of the spiral coil 51 on one end side of the main plate 61; a drive gear 63 provided on the one end side of the main plate 61; a drive shaft 64 connecting the joint unit 62 to the drive gear 63; and the like.

(48) The main plate 61 preferably is a synthetic resin molded article having sufficient rigidity, and includes a medium cylindrical portion 61a provided on the one end side of the main plate 61; a small cylindrical portion 61b provided adjacent to the medium cylindrical portion 61a; and a large semi-cylindrical portion 61c provided on the other end side of the main plate 61. A lower side of the small cylindrical portion 61b and a lower half of the large semi-cylindrical portion 61c are open.

(49) Another end portion of the conveyance hose 45 is engaged and fixed to the medium cylindrical portion 61a. The other end portion 51c of the spiral coil 51 projects from the other end portion of the conveyance hose 45, reaches inside the small cylindrical portion 61b, and is coupled and locked to the joint unit 62 inside the small cylindrical portion 61b. A pitch P1c at the other end portion 51c of the spiral coil 51 preferably is set to be narrower than the pitch P1 near the center of the spiral coil 51. In the other end portion 51c of the spiral coil 51, an engagement portion 51d configured by bending an end piece of the spiral coil 51 at a right angle or a substantially right angle is provided.

(50) The joint unit 62 is a synthetic resin (for example, ABS) molded article having sufficient rigidity, and includes a cylindrical shaft 62a; two projections 62b (one of the projections is not illustrated) each installed in a protruding manner on an outer periphery of the cylindrical shaft 62a in an opposite direction from each other at a half distance of the pitch P1a; a fitting recess 62c; and a round plate 63d.

(51) The joint unit 62 is inserted inside the other end portion 51c of the spiral coil 51. The spiral coil 51 passes through each of the projections 62b of the joint unit 62, and the engagement portion 51d of the spiral coil 51 is fitted into the fitting recess 62c of the joint unit 62. Thus, the other end portion 51c of the spiral coil 51 is coupled and locked to the joint unit 62.

(52) The drive shaft 64 preferably is a metal shaft and is pivotally supported by being passed through a hole of a bearing portion 65, which is fitted to an inward opening end of the small cylindrical portion 61b, and a hole of a bearing portion 66, which is fitted to an inward opening end of the large semi-cylindrical portion 61c. One end of the drive shaft 64 is connected and fixed to the joint unit 62 inside the small cylindrical portion 61b, and the other end of the drive shaft 64 is connected and fixed to the drive gear 63 inside the large semi-cylindrical portion 61c.

(53) As described above, the waste toner recovery unit 44 is placed on the shelf la (illustrated in FIG. 2) inside the image forming device 1. On the shelf 1a, there is provided a drive motor unit (not illustrated), which rotary drives the drive gear 63, and the drive gear 63 is rotary driven by this drive motor unit.

(54) In the developer conveyance device 41 having this configuration, when the drive gear 63 of the waste toner recovery unit 44 is rotary driven, the drive shaft 64 and the joint unit 62 are rotated. The other end portion 51c of the spiral coil 51, which is coupled and locked to the joint unit 62, is rotated, and the entire spiral coil 51 is rotated inside the conveyance hose 45. Then, in the waste toner receiving unit 43, the one end portion 51a of the spiral coil 51 is rotated, and the shaft member 52, which is coupled and locked to the one end portion 51a, is rotated, such that the spiral screw 52b of the shaft member 52 is also rotated.

(55) Since the direction of the spiral of the spiral coil 51 and the direction of the spiral of the spiral screw 52b of the shaft member 52 are the same, by setting a direction of rotation of the spiral coil 51 and that of the spiral screw 52b as appropriate, it is possible to set a direction of conveyance of the waste toner by the spiral coil 51 and that by the spiral screw 52b to a direction from the waste toner receiving unit 43 to the waste toner recovery unit 44.

(56) In this state, when the waste toner that has been removed and conveyed from the surface of the photoreceptor drum 15 by the cleaning device 14 is conveyed and discharged to the inside of the cylindrical cover 43a of the waste toner receiving unit 43, the waste toner is naturally dropped to the opening 46d of the cylindrical portion 46b. Thus, the waste toner drops on the one end portion 51a of the spiral coil 51 and the spiral screw 52b inside the cylindrical portion 46b through the opening 46d. Then, the spiral coil 51 and the spiral screw 52b rotate in the same direction and send the waste toner from the cylindrical portion 46b to the conveyance hose 45. Further, the waste toner is conveyed to the waste toner recovery unit 44 by the spiral coil 51 inside the conveyance hose 45. When it reaches the small cylindrical portion 61b of the waste toner recovery unit 44, since the lower side of the small cylindrical portion 61b is opened, it is dropped and discharged from the small cylindrical portion 61b to the waste toner bottle 42, and is housed and recovered in the waste toner bottle 42.

(57) Here, since a moving space of the waste toner is limited inside the conveyance hose 45, it is possible to efficiently convey the waste toner by using the spiral coil 51. In contrast, at the opening 46d of the cylindrical portion 46b, since an upper side of the spiral coil 51 is opened, the waste toner is easily moved in a vertical direction, such that a conveyance efficiency of the waste toner is decreased when only the spiral coil 51 is used.

(58) In the developer conveyance device 41 of the first preferred embodiment, however, the spiral screw 52b is arranged inside the one end portion 51a of the spiral coil 51, and the spiral coil 51 and the spiral screw 52b are both rotated, accompanied by rotation of the spiral coil 51, even if the waste toner tries to pass through the one end portion 51a of the spiral coil 51 and move in the vertical direction, movement of the waste toner in the vertical direction is blocked by the spiral screw 52b, such that the waste toner is conveyed by the spiral screw 52b. Since the waste toner hardly passes through the spiral coil 51 in the vertical direction, the waste toner is also conveyed by the one end portion 51a of the spiral coil 51. That is, the waste toner is surely conveyed by the spiral screw 52b and the one end portion 51a of the spiral coil 51.

(59) Since the spiral screw 52b is extended to an area near the conveyance hose 45 relative to the opening 46d of the cylindrical portion 46b (toner conveyance direction), the waste toner is surely conveyed from the opening 46d to the inside of the conveyance hose 45.

(60) In a situation where solidification of the waste toner is progressing, even if the spiral coil 51 is elastically deformed by being buried in the waste toner, the spiral screw 52b is not elastically deformed, such that a conveyance performance of the waste toner of the spiral screw 52b is maintained, and the solidification of the waste toner is effectively prevented.

(61) Further, since the spiral coil 51 and the spiral screw 52b are integrally rotated, and the pitch P2 of the spiral screw 52b preferably is set to be sufficiently longer than the pitch P1a of the one end portion 51a of the spiral coil 51, a conveyance speed of the waste toner by the spiral screw 52b becomes faster than a conveyance speed of the waste toner by the one end portion 51a of the spiral coil 51, such that at the opening 46d of the cylindrical portion 46b, the waste toner is more surely conveyed by the spiral screw 52b. Due to a difference between the conveyance speed by the spiral screw 52b and the conveyance speed by the one end portion 51a of the spiral coil 51, the solidification of the waste toner is effectively prevented.

(62) Second Preferred Embodiment

(63) FIG. 12 is a sectional view schematically illustrating a developer conveyance device of a second preferred embodiment of the present invention. As illustrated in FIG. 12, in a developer conveyance device 41A of the second preferred embodiment, one spiral coil 51 is rotatably inserted inside the conveyance hose 45. A plurality of screw members 68 is inserted inside the spiral coil 51, and each of the screw members 68 is fixed to a plurality of places of the spiral coil 51 in a lengthwise direction.

(64) FIG. 13 is a perspective view illustrating the screw member 68. As illustrated in FIG. 13, the screw member 68 is a synthetic resin (for example, ABS) molded article having sufficient rigidity, and includes a cylindrical shaft 68a; a spiral screw 68b on an outer periphery of the cylindrical shaft 68a; two projections 68c and 68d each installed in a protruding manner on an outer periphery of one end portion of the cylindrical shaft 68a in an opposite direction from each other at a half distance of the pitch P1 of the spiral coil 51; and two projections 68e and 68f each installed in a protruding manner on an outer periphery of the other end of the cylindrical shaft 68a in an opposite direction from each other at a half distance of the pitch P1. A direction of a spiral of the spiral screw 68b of the screw member 68 is the same as a direction of a spiral of the spiral coil 51. The pitch P2 of the spiral screw 68b preferably is set to be sufficiently longer than the pitch P1 of the spiral coil 51.

(65) The screw member 68 is arranged so as to be inserted inside the spiral coil 51. The spiral coil 51 is inserted into a slit 68g of each of the projections 68c and 68d on an outer periphery of the one end portion of the cylindrical shaft 68a, and the spiral coil 51 is adhered to each of the projections 68c and 68d. Similarly, the spiral coil 51 is inserted into the slit 68g of each of the projections 68e and 68f on an outer periphery of the other end portion of the cylindrical shaft 68a, and the spiral coil 51 is adhered to each of the projections 68e and 68f. Thus, the screw member 68 is fixed to inside of the spiral coil 51.

(66) In this developer conveyance device 41a of the second preferred embodiment, when the spiral coil 51 is rotated, each of the screw members 68 is also rotated, such that waste toner inside the conveyance hose 45 is promptly conveyed in one direction by the spiral coil 51 and the spiral screw 68b of each of the screw members 68.

(67) In a situation where solidification of the waste toner is progressing, even if the spiral coil 51 is elastically deformed by being buried in the waste toner, the spiral screw 68b is not elastically deformed, such that a conveyance performance of the waste toner by the spiral screw 68b is maintained, and the solidification of the waste toner is effectively prevented.

(68) Further, since a pitch P2 of the spiral screw 68b preferably is set to be sufficiently longer than the pitch P1 of the spiral coil 51, a conveyance speed of the waste toner by the spiral screw 68b becomes faster than a conveyance speed of the waste toner by the spiral coil 51. Due to a difference between the conveyance speed by the spiral screw 68b and the conveyance speed by the spiral coil 51, the solidification of the waste toner can be more effectively prevented.

(69) Third Preferred Embodiment

(70) FIG. 14 is a sectional view illustrating an image forming device, to which a developer conveyance device of a third preferred embodiment of the present invention is applied, viewed from a front side. An image forming device 1A is provided with the printing unit 2, the image reading device 3, the original conveyance device 4, the paper supply device 6, and the like.

(71) Image data handled in the image forming device 1A is image data corresponding to a color image using each of colors of black (K), cyan(C), magenta (M), and yellow (Y) or image data corresponding to a monochrome image using a single color (for example, black). Accordingly, in the printing unit 2, in order to form toner images of four types corresponding to each of the colors, there are preferably provided four developing devices 72, four photoreceptor drums 73, four drum cleaning devices 74, and four charging devices 75, such that four image stations Pa, Pb, Pc, and Pd, which are respectively associated with black, cyan, magenta, and yellow, are configured.

(72) In any of the image stations Pa, Pb, Pc, and Pd, after toner remaining on a surface of the photoreceptor drum 73 is removed by the drum cleaning device 74, the surface of the photoreceptor drum 73 is uniformly charged with a predetermined electric potential by the charging device 75. The surface of the photoreceptor drum 73 is exposed by an optical scanning device 71 to form an electrostatic latent image on the surface thereof, and the electrostatic latent image on the surface of the photoreceptor drum 73 is developed by the developing device 72, such that the toner image is formed on the surface of the photoreceptor drum 73. Thus, the toner image of each of the colors is formed on the surface of each of the photoreceptor drums 73.

(73) Subsequently, after the toner remaining on a surface of an intermediate transfer belt 76 is removed by a belt cleaning device 77 while an intermediate transfer belt 76 is circularly moved in an arrow direction G, the toner image of each of the colors on the surface of each of the photoreceptor drums 73 is transferred and overlapped on the intermediate transfer belt 76 one by one, such that a color toner image is formed on the intermediate transfer belt 76.

(74) A nip zone is provided between the intermediate transfer belt 76 and a secondary transfer roller 78a of a secondary transfer device 78, and while conveying recording paper, which has been conveyed through a paper conveyance path R1, by sandwiching it in the nip zone, the color toner image on a surface of the intermediate transfer belt 76 is transferred on the recording paper. Then, the recording paper is heated and pressurized being sandwiched between a heating roller 82 of a fixing device 81 and a pressurizing roller 83, such that the color toner image on the recording paper is fixed.

(75) From the paper supply device 6, the recording paper is drawn out and is supplied one sheet by one sheet. The recording paper is conveyed through the paper conveyance path R1, is passed through the secondary transfer device 78 and the fixing device 81, and is carried out to a paper ejection tray 86 through a paper ejection roller 85. In this paper conveyance path R1, there are preferably arranged: a resist roller 87, which starts conveyance of the recording paper after temporarily stopping the recording paper and aligning a leading end of the recording paper according to transfer timing of the color toner image in the nip zone between the intermediate transfer belt 76 and the secondary transfer roller 78a; each of conveyance rollers 88, which prompts conveyance of the recording paper; a paper ejection roller 85; and the like.

(76) Further, in a case where image formation is performed not only on a front surface of the recording paper but also on a back surface thereof, the recording paper is conveyed in an opposite direction from the paper ejection roller 85 to a turn over path Rr. The recording paper is turned over from the front surface to the back surface, and the recording paper is guided again to the resist roller 87. Similarly with the front surface of the recording paper, an image is recorded and fixed on the back surface of the recording paper, and the recording paper is discharged to the paper ejection tray 86.

(77) FIG. 15 is a view schematically illustrating a developer conveyance device 41B and a waste toner bottle 95 of the third preferred embodiment arranged in the image forming device 1A viewed from a rear side of the image forming device 1A. Here, in any of the image stations Pa, Pb, Pc, and Pd, the drum cleaning device 74 removes the toner remaining on the surface of the photoreceptor drum 73. The removed waste toner is conveyed to a front side of the image forming device 1A by a screw extending in a shaft direction of the photoreceptor drum 73, and the waste toner is discharged to a vertically standing pipe 91. Thus, the toner remaining on the surface of the four photoreceptor drums 73 is removed by the four drum cleaning devices 74. The waste toner is conveyed to the front side of the image forming device 1A by each of the drum cleaning devices 74, and the waste toner is discharged to the four pipes 91.

(78) Similarly, the belt cleaning device 77 removes the toner remaining on the surface of the intermediate transfer belt 76, and the removed waste toner is conveyed to the front side of the image forming device 1A by a screw extending in a width direction of the intermediate transfer belt 76, such that the waste toner is discharged to a vertically standing pipe 92.

(79) Accordingly, the waste toner discharged to each of the pipes 91 and 92 is naturally dropped to each of the openings 94a and 94b of a conveyance hose 94 of the developer conveyance device 41b through each of the pipes 91 and 92. In the developer conveyance device 41b, the waste toner is conveyed to an upper side of the waste toner bottle 95 through the conveyance hose 94, and the waste toner is discharged to and recovered in the waste toner bottle 95.

(80) FIG. 16 is a view schematically illustrating the developer conveyance device 41b of the third preferred embodiment. As illustrated in FIG. 16, in the developer conveyance device 41B, one spiral coil 51 is rotatably inserted inside the conveyance hose 94. Furthermore, in the opening 94a of the conveyance hose 94 communicating with the pipe 91 of the image station Pa, the shaft member 52 is inserted into the one end portion 51a of the spiral coil 51. The one end portion 51a of the spiral coil 51 is coupled and locked to the shaft member 52, such that the one end portion 51a of the spiral coil 51 and the shaft member 52 are rotatably supported. This supporting structure of the one end portion 51a of the spiral coil 51 and the shaft member 52 is as described above with reference to FIGS. 4 and 6.

(81) Further, in each of the openings 94a of the conveyance hose 94 communicating with each of the pipes 91 of another of the image stations Pb, Pc, and Pd, the screw member 68 is inserted inside the spiral coil 51 and is fixed thereto. Similarly, in the opening 94b of the conveyance hose 94 communicating with the pipe 92 of the belt cleaning device 77, the screw member 68 is inserted inside the spiral coil 51 and is fixed thereto. A fixing structure of the screw member 68 to the spiral coil 51 is as described above with reference to FIGS. 12 and 13.

(82) The joint unit 62 is inserted into the other end portion 51c of the spiral coil 51, and the other end portion 51c of the spiral coil 51 is coupled and locked to the joint unit 62. A locking structure of the joint unit 62 to the other end portion 51c of the spiral coil 51 is as described above with reference to FIG. 11.

(83) In the developer conveyance device 41B having this configuration, the joint unit 62 is rotary driven, and the spiral coil 51, the shaft member 52, and each of the screw members 68 are rotary driven in a predetermined direction inside the conveyance hose 94. In this state, when the waste toner is naturally dropped into the opening 94a of the conveyance hose 94 through the pipe 91 of the image station Pa, by the spiral coil 51 and by the spiral screw 52b of the shaft member 52, the waste toner is sent through the conveyance hose 94 in a direction nearing the waste toner bottle 95. When the waste toner is naturally dropped into each of the openings 94a of the conveyance hose 94 through the pipe 91 of another of the image stations Pb, Pc, and Pd, the waste toner is conveyed by the spiral coil 51 and by a spiral screw 68b of each of the screw members 68 in a direction nearing the waste toner bottle 95 through the conveyance hose 94. Similarly, when the waste toner is naturally dropped into the opening 94b of the conveyance hose 94 through the pipe 92 of the belt cleaning device 77, the waste toner is conveyed by the spiral coil 51 and by the spiral screw 68b of the screw member 68 in the direction nearing the waste toner bottle 95 through the conveyance hose 94. Thus, the waste toner discharged to each of the pipes 91 and 92 is naturally dropped into each of the openings 94a and 94b of the conveyance hose 94 and is conveyed by the spiral coil 51, the spiral screw 52b of the shaft member 52, and the spiral screw 68b of each of the screw members 68 in the direction nearing the waste toner bottle 95 through the conveyance hose 94.

(84) Then, when the waste toner is conveyed to the joint unit 62 through the conveyance hose 94, since a lower side of the joint unit 62 is opened, the waste toner is discharged from the joint unit 62 to the waste toner bottle 95, where it is recovered.

(85) In the developer conveyance device 41B of the third preferred embodiment as well, the waste toner inside the conveyance hose 45 is quickly conveyed by the spiral coil 51, the spiral screw 52b of the shaft member 52, and the spiral screw 68b of each of the screw members 68.

(86) The spiral screw 52b and each of the spiral screws 68b are extended in the direction nearing the waste toner bottle 95 relative to each of the openings 94a and 94b of the conveyance hose 94. Accordingly, the waste toner is surely conveyed from each of the openings 94a and 94b to inside of the conveyance hose 94.

(87) In a situation where solidification of the waste toner is progressing, even if the spiral coil 51 is elastically deformed being buried in the waste toner, the spiral screw 52b and each of the spiral screws 68b are not elastically deformed, such that a conveyance performance of the waste toner by the spiral screw 52b and each of the spiral screws 68b is maintained, and the solidification of the waste toner is effectively prevented.

(88) Further, a pitch P2 of the spiral screw 52b and each of the spiral screws 68b is sufficiently longer than pitches P1 and P1a of the spiral coil 51, such that a conveyance speed of the waste toner by the spiral screw 52b and each of the spiral screws 68b is faster than a conveyance speed of the waste toner by the spiral coil 51. Due to a difference between the conveyance speed by the spiral screw 52b and each of the spiral screws 68b and the conveyance speed by the spiral coil 51, the solidification of the waste toner is more effectively prevented.

(89) Note, however, that in each of the above-described preferred embodiments, the pitch P2 of the spiral screw 52b and each of the spiral screws 68b is set to be longer than the pitches P1 and P1a of the spiral coil 51. However, it is also possible to set such that the pitch P2 is the same as the pitch P1 or the pitch P1a or to set such that the pitch P2 is shorter than the pitch P1 or the pitch P1a. It is also possible to apply a coil spring in place of a spiral coil.

(90) Further, in each of the above-described preferred embodiments, the developer conveyance device is applied to convey the waste toner. However, it is also possible to apply the developer conveyance device according to various preferred embodiments of the present invention to convey unused toner from a toner cartridge to a developing device.

(91) As above, the preferred embodiments and modifications of the present invention have been described with reference to the attached drawings. However, it is needless to say that the present invention is not to be limited to these examples.

(92) While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.