JP4444086B2 - Toner transfer mechanism, developing unit, and image forming apparatus - Google Patents

Description

  The present invention relates to a toner transfer mechanism for transferring toner for developing an electrostatic latent image on a photosensitive member, a developing unit for supplying the toner to the photosensitive member, and an image including the toner transfer mechanism or the developing unit. The present invention relates to a forming apparatus.

  2. Description of the Related Art Image forming apparatuses such as electrophotographic printers, copiers, facsimiles, and multifunction machines form an image by developing an electrostatic latent image using toner.

In such an image forming apparatus, for example, as shown in Patent Document 1, toner transfer for transferring toner by free fall from one toner storage tank (toner reservoir) to another toner storage tank (main body case) A path (first cylinder) may be provided to transfer toner between different toner storage tanks.
Japanese Patent Laid-Open No. 7-098542 (Publication date: April 11, 1995) JP 11-24524 A (publication date: January 29, 1999) JP 2003-29514 A (publication date: January 31, 2003)

  However, in the case where the toner is transferred by free fall, if the image forming apparatus is used for a long period of time, the toner adheres and stays on the wall surface of the toner supply path, and the attached and staying toner accumulates and enlarges. There arises a problem that the supply path is clogged.

  Further, according to the configurations of Patent Document 2 and Patent Document 3, a configuration is provided in which a screw-type auger having a rotation axis in the toner supply direction is provided in the above-described toner supply path, and the toner is conveyed by the stirring force of the auger. Has been. According to this configuration, since the toner in the toner supply path is forcibly conveyed by the auger, the problem that the toner supply path is clogged can be suppressed.

  However, if an auger that requires a complicated mechanism is used in the image forming apparatus, the image forming apparatus is unnecessarily enlarged. Further, if an auger that requires a complicated mechanism is used, the maintenance of the apparatus becomes complicated. Further, the auger described above is an expensive member. If this auger is used, the cost of the image forming apparatus is increased.

  Therefore, when transferring toner from one place to another, it is more cost-effective and space-saving to use a mechanism that transfers toner by free fall to the end without using the above-mentioned configuration for forcibly transporting toner by an auger. It is preferable from the viewpoint of simplification of maintenance.

  Therefore, there is a demand for a mechanism that does not cause clogging in the toner transfer path without using the above-described auger in a mechanism that transfers toner by free fall.

  An object of the present invention is to provide a toner transfer mechanism, a developing unit, and an image forming apparatus capable of suppressing clogging generated in a toner transfer path in a toner transfer path for transferring toner by free fall.

  In order to achieve the above object, the toner transfer mechanism of the image forming apparatus of the present invention is provided with a toner transfer path for transferring toner by free fall from the toner sending side to the toner receiving side, and the toner transfer path, A transfer assisting member for assisting the transfer of the toner by moving in the toner transfer direction.

  According to the above configuration, in the toner transfer path for transferring the toner from the toner sending side to the toner receiving side by free fall, by moving in the toner transfer direction (direction from the toner sending side to the toner receiving side) A transfer assisting member for assisting the transfer of the toner is provided.

  Therefore, in the toner transfer path, when the toner being transferred approaches or contacts the transfer assisting member due to free fall, the transfer of the toner is assisted and promoted by the moving force of the transfer assisting member.

  Thereby, in the toner transfer path, the retention of toner in the vicinity of the transfer auxiliary member can be suppressed, so that the toner transfer path can be prevented from being clogged due to accumulation and enlargement of the stay.

  That is, the clogging of the toner supply path can be suppressed without using the auger disclosed in Patent Documents 2 and 3.

  The augers disclosed in Patent Documents 2 and 3 are configured to convey the toner by rotating the screw, and are not configured to move in the toner transfer direction.

  The toner transfer mechanism of the present invention may also be applied to a developing unit including a toner hopper, a developing device that supplies toner to the photoreceptor, and a toner transfer path that communicates the toner hopper and the developing device. Is possible.

  In this case, the present invention communicates the toner hopper for storing toner, the developing device for supplying the toner from the toner hopper and supplying the toner to the photosensitive member, the toner hopper and the developing device, A toner transfer path for transferring toner from the toner hopper to the developing device by free-fall, and a transfer auxiliary member provided in the toner transfer path for assisting transfer of the toner by moving in the toner transfer direction; Can be expressed as a developing unit of an image forming apparatus.

  Further, a configuration in which the above-described toner transfer mechanism and / or developing unit of the present invention is included in the image forming apparatus is also within the scope of the present invention.

  In the toner transfer mechanism of the present invention, the transfer assisting member moves in the toner transfer path with the toner delivery side as the upstream and the toner receiving side as the downstream, and outside the toner transfer path from the downstream to the above. It is preferable that the circulating drive member return upstream.

  According to the above configuration, the transfer assisting member moves only in the toner transfer direction (the direction from the toner sending side to the toner receiving side) in the toner transfer path. There is an effect that it is possible to assist and promote toner transfer.

  Further, if a belt member or a string-like member is used as such a circulation drive member, there is an effect that a complicated mechanism is not required, and a simple configuration, low cost, and space saving can be realized.

  Furthermore, in the toner transfer mechanism of the present invention, when the circulation drive member is the belt member, the surface of the belt member is preferably an uneven shape.

  According to this configuration, since the surface of the belt member has an uneven shape, the protruding portion of the unevenness moves in the toner transfer direction. Accordingly, the driven protrusions scrape the toner in the toner transfer direction, further assisting and promoting toner transfer. As a result, the toner can be further prevented from staying in the toner transfer path.

  Furthermore, the toner transfer mechanism of the present invention preferably includes a cover member that covers the return side of the circulation drive member.

  According to the above configuration, the return side of the circulation drive member is arranged outside the toner transfer path. Therefore, when toner adheres to the circulation drive member in the toner transfer path, there is a possibility that the toner falls from the circulation drive member that is moving in return, and the toner is scattered outside.

  So, according to the said structure, the cover member which covers the said return side in the said circulation drive member is provided. As a result, even if the toner falls from the circulating drive member during the return movement, the toner can be received by the cover member, and the inconvenience that the toner is scattered outside can be suppressed.

  Further, in the developing unit of the present invention described above, the transfer assisting member moves in the toner transfer path with the toner sending side as the upstream and the toner receiving side as the downstream, and outside the toner transfer path from the downstream. A circulation drive member that returns to the upstream, and includes a toner supply roller that sends toner from the toner hopper to a toner transfer path, and a drive roller that drives the circulation drive member, and the toner supply roller, the drive roller, The driving force may be applied from the same driving source.

  According to the above configuration, the toner replenishing roller that sends toner from the toner hopper to the toner transfer path and the driving roller that drives the circulation driving member are driven by the driving force from the same driving source. Space saving and cost reduction can be achieved as compared with the configuration in which the driving roller and the toner supply roller are separately provided with driving sources.

  As described above, the toner transfer mechanism of the image forming apparatus according to the present invention includes the toner transfer path for transferring the toner by free fall from the toner sending side to the toner receiving side, and the toner transfer path. And a transfer assisting member that assists the transfer of the toner by moving in the direction.

  The developing unit of the image forming apparatus of the present invention includes a toner hopper that stores toner, a developing device that supplies toner from the toner hopper and supplies the toner to the photosensitive member, the toner hopper, and the developing unit. A toner transfer path that communicates with the apparatus and transfers the toner from the toner hopper to the developing apparatus by free fall, and is provided in the toner transfer path, and moves the toner by moving in the toner transfer direction. And a transfer assisting member to assist.

  Furthermore, the image forming apparatus of the present invention includes the above-described toner transfer mechanism or developing unit.

  Therefore, the toner staying in the vicinity of the transport assisting member can be suppressed in the toner transporting path, so that the toner transporting path can be prevented from clogging due to accumulation and enlargement of the staying.

  An embodiment of the present invention will be described below with reference to the drawings. In the following, first, an image forming apparatus including a developing unit provided with a toner transfer mechanism according to an embodiment of the present invention will be described, and then the developing unit will be described.

[Configuration of image forming apparatus]
FIG. 2 is a longitudinal sectional view showing the configuration of the image forming apparatus according to this embodiment.

  The image forming apparatus according to the present embodiment (hereinafter referred to as “the present image forming apparatus”) forms multi-color and single-color images on a predetermined sheet (recording medium) in accordance with image data transmitted from the outside. To do. As shown in FIG. 2, the image forming apparatus includes an exposure unit 1, a developing unit 2, a photosensitive drum 3, a charger 5, a cleaner unit 4, an intermediate transfer belt unit 8, a fixing unit 12, and a paper transport path S. The paper feed cassette 10 and the paper discharge tray 15 are configured.

  Note that image data handled in the image forming apparatus corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Therefore, the developing unit 2 (2a, 2b, 2c, 2d), the photosensitive drum 3 (3a, 3b, 3c, 3d), the charger 5 (5a, 5b, 5c, 5d), the cleaner unit 4 (4a, 4b, 4c and 4d) are provided so that four types of latent images corresponding to the respective colors are formed, each of which is set to a black, b to cyan, c to magenta, and d to yellow. This constitutes four image stations.

  The photosensitive drum 3 is disposed (mounted) inside the image forming apparatus.

  The charger 5 is a contact-type roller as shown in FIG. 2, and is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. The charger 5 may be a brush-type charger or a charger-type (for example, corona charger) charger, in addition to a contact-type roller.

  As shown in FIG. 2, the exposure unit 1 is a laser scanning unit (LSU) including a laser irradiation unit and a reflection mirror.

  This exposure unit 1 has a function of forming an electrostatic latent image corresponding to image data on its surface by exposing a charged photosensitive drum 3 according to input image data. is there.

  For example, an EL (electro luminescence) or LED (light emitting diode) writing head in which light emitting elements are arranged in an array may be used as the exposure unit 1.

  The developing unit 2 includes a developing device that visualizes electrostatic latent images formed on the respective photosensitive drums 3 with toners (developers) of K, C, M, and Y, and a toner hopper that stores the toner. A unit including The configuration of the developing unit 2 will be described in detail later.

  The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The intermediate transfer belt unit 8 disposed above the photosensitive drum 3 includes an intermediate transfer belt (transfer material) 7, an intermediate transfer belt driving roller 71, an intermediate transfer belt tension roller 73, an intermediate transfer belt driven roller 72, and an intermediate transfer. A roller 6 (6a, 6b, 6c, 6d) and an intermediate transfer belt cleaning unit 9 are provided.

  The intermediate transfer belt drive roller 71, the intermediate transfer belt tension roller 73, the intermediate transfer roller 6, the intermediate transfer belt driven roller 72, and the like stretch the intermediate transfer belt 7, and rotate the intermediate transfer belt 7 in the direction of arrow B in the figure. It is to be driven.

  The intermediate transfer belt 7 is provided so as to come into contact with the respective photosensitive drums 3, and the toner images of the respective colors formed on the photosensitive drums 3 are sequentially transferred onto the intermediate transfer belt 7 and transferred (1 Next transfer), a color toner image, that is, a multicolor toner image is formed on the intermediate transfer belt 7.

  The intermediate transfer belt 7 is formed in an endless shape using a film having a thickness of about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by the intermediate transfer roller 6 in contact with the back side of the intermediate transfer belt 7.

  The intermediate transfer roller 6 is rotatably supported by the intermediate transfer roller mounting portion of the intermediate transfer belt tension roller 73. The intermediate transfer roller 6 is applied with a high-voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) in order to transfer the toner image. This transfer bias is released. This transfer bias is for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 7.

  The intermediate transfer roller 6 is a roller in which a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm is used as a base material (base), and the surface of the base material is covered with a conductive elastic material. In addition, as this elastic material, for example, EPDM (ethylene propylene dien monomer), urethane foam or the like is used. With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 7. In the present embodiment, the intermediate transfer roller 6 is used as a transfer electrode for applying a transfer bias. However, a brush or the like can also be used.

  As described above, the electrostatic images visualized on the respective photosensitive drums 3 according to the respective hues are stacked on the intermediate transfer belt 7 and become an image corresponding to the image data input to the apparatus.

  The images stacked in this manner are conveyed to the secondary transfer position, which is the contact position between the sheet and the intermediate transfer belt 7, by the rotation of the intermediate transfer belt 7, and the transfer roller 11 (transfer) disposed at the secondary transfer position. Device). The intermediate transfer belt 7 and the transfer roller 11 are pressed against each other at a predetermined nip.

  Further, a voltage (transfer voltage) for transferring the toner onto the sheet (secondary transfer) is applied to the transfer roller 11, and the transfer roller 11 releases the transfer voltage (the charge polarity (−) of the toner). Is high voltage of reverse polarity (+).

  Hereinafter, transfer from the intermediate transfer belt 7 to the paper is referred to as secondary transfer, and the voltage applied to the transfer roller 11 is referred to as secondary transfer voltage, which is distinguished from transfer from the photosensitive drum 3 to the intermediate transfer belt 7.

  Further, in order to form a nip between the transfer roller 11 and the intermediate transfer belt drive roller 71 steadily, either the transfer roller 11 or the intermediate transfer belt drive roller 71 is made of a hard material (metal or the like), and the other Is formed of a soft material such as an elastic roller (elastic rubber roller, foaming resin roller, or the like).

  Further, the toner that is not transferred onto the sheet by the transfer roller 11 and remains on the intermediate transfer belt 7 causes toner color mixing in the next step, and is therefore removed and collected by the intermediate transfer belt cleaning unit 9. Is set to

  The intermediate transfer belt cleaning unit 9 includes a cleaning blade as a cleaning member that comes into contact with the intermediate transfer belt 7, and the contact point of the cleaning blade in the intermediate transfer belt 7 is supported by the intermediate transfer belt driven roller 72 from the back side. ing.

  The paper feed cassette 10 is a tray for storing sheets (sheets) used for image formation, and is provided below the exposure unit 1 in the image forming apparatus.

  Further, the paper discharge tray 15 provided in the upper part of the image forming apparatus is a tray for placing printed sheets face down.

  Further, the image forming apparatus is provided with a substantially vertical sheet conveyance path S for sending the sheet of the sheet feeding cassette 10 to the sheet discharge tray 15 via the transfer roller 11 and the fixing unit 12.

  In addition to the transfer roller 11 described above, a pickup roller 16a, a registration roller 14, a fixing unit 12, a conveyance roller 25 that conveys a sheet, and the like are disposed in the vicinity of the sheet conveyance path S from the paper feed cassette 10 to the paper discharge tray 15. Is arranged.

  The conveyance rollers 25 (25a to 25h) are a set of small rollers for promoting and assisting conveyance of the sheet, and a plurality of conveyance rollers 25 are provided along the sheet conveyance path S.

  The pickup roller 16 a is a drawing roller that is provided at the end of the paper feed cassette 10 and that feeds sheets one by one from the paper feed cassette 10 to the paper transport path S.

  The registration roller 14 temporarily holds the sheet conveyed in the sheet conveyance path S. The registration roller 14 has a function of conveying the sheet to the secondary transfer position at a timing when the leading edge of the toner image on the intermediate transfer belt 7 is aligned with the leading edge of the sheet.

  The fixing unit 12 includes a heat roller 31, a pressure roller 32, and the like, and the heat roller 31 and the pressure roller 32 rotate with a sheet interposed therebetween.

  The heat roller 31 is set by the control unit to have a predetermined fixing temperature based on a signal from a temperature detector (not shown), and is transferred to the sheet by thermocompression bonding the sheet together with the pressure roller 32. The resulting multicolor toner image is melted, mixed, and pressed to thermally fix the sheet.

  The sheet after the fixing of the multicolor toner image is transported to the reverse paper discharge path of the paper transport path S by the transport rollers 25b and 25c, and is reversed (with the multicolor toner image facing downward). The paper is discharged onto the paper discharge tray 15.

  Next, the sheet conveyance path will be described in detail. The image forming apparatus is provided with a paper feed cassette 10 that stores sheets in advance, and a manual paper feed tray 20 that does not need to open and close the paper feed cassette 10 when a user prints a small number of sheets. Is arranged.

  A pickup roller 16b is arranged between the manual paper feed tray 20 and the paper transport path S so as to guide the sheets one by one to the paper transport path S.

  The sheet conveyed from the sheet feeding cassette 10 is conveyed to the registration roller 14 by the conveying roller 25a in the sheet conveying path S, and the transfer roller 11 is aligned with the leading edge of the sheet and the leading edge of the toner image on the intermediate transfer belt 7. And the toner image is transferred onto the sheet.

  Thereafter, the sheet passes through the fixing unit 12 so that the unfixed toner on the sheet is melted and fixed by heat, and is discharged onto the sheet discharge tray 15 through the conveyance rollers 25b and 25c (when one-side printing is requested). ).

  On the other hand, the sheets stacked on the manual paper feed tray 20 are fed by the pickup roller 16b, reach the registration roller 14 through a plurality of transport rollers 25f, 25d, and 25e, and thereafter feed from the paper feed cassette 10. The paper is discharged to the paper discharge tray 15 through the same process as the paper sheet (when single-sided printing is requested).

  At this time, when the content of the print request is a double-sided print request, the trailing edge of the sheet that has finished the single-sided printing and has passed through the fixing unit 12 as described above is chucked by the conveyance roller 25c. The sheet is guided to the transport rollers 25g and 25h in the paper transport path S by the reverse rotation of the transport roller 25c. Thereafter, the sheet is printed on the back surface through the registration roller 14 and then discharged to the paper discharge tray 15.

[Configuration of development unit]
Next, details of the configuration of the developing unit 2 included in the image forming apparatus will be described. FIG. 1 is a longitudinal sectional view of the developing unit 2.

  As shown in FIG. 1, the developing unit 2 includes a toner hopper 101, a toner transfer mechanism 102, and a developing device 103. The toner transfer mechanism 102 is for supplying toner to the developing device 103, and includes a toner transfer pipe (toner transfer path) 200, a drive belt 201, a drive roller 202, and driven rollers 203a and 203b. .

  The toner hopper 101 is a toner storage tank that is disposed higher than the developing device 103 and stores unused toner (powdered toner).

  The toner hopper 101 has a toner outlet 101 a formed at the bottom and a toner replenishing roller 110 inside the toner hopper 101.

  The toner replenishing roller 110 is a roller made of a porous elastic material such as urethane sponge, for example, for supplying the toner in the toner hopper 101 little by little to the toner delivery port 101a.

  The developing device 103 is disposed so as to face the photosensitive drum 3, and supplies toner to the surface of the photosensitive drum 3 to visualize the electrostatic latent image formed on the surface of the photosensitive drum 3. It is.

  As shown in FIGS. 1 and 5, the developing device 103 includes a developer storage tank 111, stirring rollers 112 a and 112 b and a development roller 114 provided in the developer storage tank 111.

  FIG. 5 is a schematic diagram showing the inside of the developer storage tank 111 from the upper part in the vertical direction. In the present embodiment, as shown in FIG. 5, one end side in the rotation axis direction of the stirring roller 112a is a front side, and the other end side is a rear side.

  The developer storage tank 111 is a tank for storing a two-component developer composed of toner and carrier.

  As shown in FIGS. 1 and 5, in the developer storage tank 111, a toner receiving port 111a is formed on the upper side and on the front side of the stirring roller 112a.

  As shown in FIG. 5, the stirring rollers 112a and 112b are screw-shaped rollers having stirring blades for stirring and transporting the developer.

  These agitating rollers 112a and 112b are set so that their outer peripheral surfaces are arranged in parallel so that they face each other via a partition plate 111b and rotate in opposite directions. That is, the rotation axes of the stirring rollers 112a and 112b are parallel to each other, but the rotation directions are opposite to each other.

  Further, the partition plate 111b extends between the stirring rollers 112a and 112b in parallel to the rotation axis direction of the rollers 112a and 112b. The partition plate 111b divides the interior of the developer storage tank 111 into a space C in which the stirring roller 112a is disposed and a space D in which the stirring roller 112b is disposed.

  Further, the partition plate 111 b is arranged such that both end portions in the rotation axis direction are separated from the wall surface of the developer storage tank 111. Thereby, the communicating path which connects the space C and the space D will be formed in the vicinity of both ends of the partition plate 111b in the rotation axis direction.

  In the present embodiment, as shown in FIG. 5, the communication path formed near the front end of the partition plate 111b is referred to as “communication path a”, and near the rear end of the partition plate 111b. The formed communication path is referred to as “communication path b”.

  As shown in FIG. 1, the developing roller 114 is a magnet roller disposed so as to be close to the photosensitive drum 3 at a position facing the photosensitive drum 3. The developing roller 114 is set so as to rotate in the direction opposite to the rotation direction of the photosensitive drum 3. The developing roller 114 is for supplying the toner in the developer storage tank 111 to the photosensitive drum 3, and a layer thickness regulating blade 115 is disposed at a position close to the outer periphery of the developing roller 114. Yes.

  Next, each component of the toner transfer mechanism 102 will be described.

  The toner transfer tube 200 transfers the toner in the toner hopper (toner delivery side) 101 to the developer storage tank (toner reception side) 111 of the developing device 103 by free fall, and replenishes the developer storage tank 111 with toner. This is the path that has been formed.

  Specifically, the toner transfer tube 200 has one opening end 200a facing the toner delivery port (toner delivery side) 101a and the other opening end 200b facing the toner reception port (toner reception side) 111a. The toner hopper 101 and the developer storage tank 111 are connected.

  As a result, the inside of the developer storage tank 111 and the inside of the toner hopper 101 in the developing device 103 are configured to communicate with each other via the toner transfer pipe 200.

  The toner transfer pipe 200 is disposed between the toner hopper 101 and the developer storage tank 111 so that the direction from the opening end 200a to the opening end 200b is parallel or substantially parallel to the vertical direction.

  A driving belt (transfer assisting member, circulation driving member, belt member) 201 is a belt member that is stretched around the outer periphery of the driven rollers 203 a and 203 b and the driving roller (driving means) 202 and is driven to circulate by driving the driving roller 202. And unevenness is formed on the belt surface.

  In addition, on the wall surface of the toner transfer tube 200, through holes 200c and 200d are formed in parallel along the vertical direction, and driven rollers 203a and 203b are disposed in the through holes 200c and 200d, respectively. Further, the driving roller 202 is disposed outside the toner transfer tube 200 so as to face both the driven rollers 203a and 203b.

  Here, the drive roller 202 is disposed such that the rotation axis thereof is perpendicular to the vertical direction and the peripheral surface thereof faces the toner transfer tube 200. Further, the driven rollers 203 a and 203 b are arranged so that their rotation axes are parallel to the rotation axis of the drive roller 202.

  If the driven rollers 203a and 203b and the driving roller 202 are arranged as described above, the driving belt 201 is stretched along the vertical direction by the driven rollers 203a and 203b in the toner transfer pipe 200 as shown in FIG. Can be made.

  Further, the driving roller 202 is driven so that the driving belt 201 moves downward in the vertical direction (the direction from the toner storage unit 101 toward the developing device 103) inside the toner transfer tube 200.

  As a result, when the toner hopper 101 side (toner delivery side) in the toner transfer pipe 200 is the upstream side and the developing device 103 side (toner reception side) in the toner transfer pipe 200 is the downstream side, the drive belt 201 It moves from the upstream side to the downstream side inside the tube 200 and returns from the downstream side to the upstream side outside the toner transfer tube 200. That is, the drive belt 201 is driven to circulate between the driven rollers 203a and 203b and the drive roller 202.

[Development unit functions]
Next, the function of the developing unit 2 described above will be described. First, the function of the developing device 103 will be described.

  In the developer storage tank 111 of the developing device 103, as shown in FIG. 5, the agitation rollers 112a and 112b are rotatively driven to circulate and convey the developer in the direction of the arrow in the figure.

  Specifically, in the space C, the developer is conveyed while being stirred from the front side to the rear side by the stirring roller 112a. The developer conveyed to the rear side of the space C passes through the communication path a and is conveyed to the space D. In the space D, the developer is conveyed while being stirred from the rear side to the front side by the stirring roller 112b. Then, the developer conveyed to the front side of the space D passes through the communication path b and is conveyed to the space C. In this way, the developer circulates in the developer storage tank 111 while being stirred.

  By such agitation and circulation movement, the developer stored in the developer storage tank 111 is uniformly dispersed.

  Further, the agitation causes the toner particles and the carrier particles to rub to generate static electricity (generation of static electricity due to friction), and the toner in the developer is charged and adheres to the carrier.

  The toner attached to the carrier is attracted to the surface of the developing roller 114 together with the carrier in the space D.

  Further, the toner attracted to the developing roller 114 together with the carrier is conveyed to a proximity position (developing area) between the developing roller 114 and the photosensitive drum 3. In this developing area, the toner on the developing roller 114 is supplied to the photosensitive drum 3.

  The developing device 103 supplies toner to the photosensitive drum 3 as described above.

  Next, the function of the toner transfer mechanism 102 for supplying toner from the toner hopper 101 to the developer storage tank 111 will be described.

  First, in the toner hopper 101, when the toner supply roller 110 is rotationally driven, the toner in the toner hopper 101 is gradually conveyed to the toner delivery port 101a.

  Then, the toner conveyed to the toner delivery port 101a falls freely into the toner transfer tube 200 through the toner delivery port 101a and the opening end 200a.

  Further, the toner dropped into the toner transfer pipe 200 is transferred to the opening end 200b by further free fall and discharged from the opening end 200b.

  Thereafter, the toner discharged from the opening end 200b falls to the vicinity of the upper part of the stirring roller 112a inside the developer storage tank 111 through the toner receiving port 111a.

  In this way, the toner stored in the toner hopper 101 is replenished to the developer storage tank 111 of the developing device 103 one after another via the toner transfer pipe 200.

  Here, as described above, the toner transfer tube 200 is a toner transfer path that transfers toner from the toner hopper (toner delivery side) 101 to the developer storage tank (toner reception side) 111 by free fall. In the present embodiment, a driving belt 201 is disposed inside the toner transfer tube 200.

  The drive belt 201 moves in the toner transfer pipe 200 in the direction from the toner hopper 101 side to the developer storage tank 111 side, that is, in the transfer direction of the free-falling toner.

  Therefore, in the toner transfer tube 200, the protrusion on the unevenness of the drive belt 201 moves in the toner transfer direction, and this protrusion scratches the toner in the toner transfer direction.

  Therefore, in the toner transfer pipe 200, the transfer of the toner by free fall is assisted and promoted by the scraping action of the protrusions.

  Here, in the toner transfer tube 200, the transfer of toner by the free fall of the toner is assisted and promoted, so that the toner can be prevented from staying inside the toner transfer tube 200, and this stay is accumulated and enlarged. 200 toner clogging can also be suppressed.

  Accordingly, the drive belt 201 inside the toner transfer tube 200 functions as a transfer assisting member that assists and promotes the transfer of toner that freely falls in the direction from the toner hopper 101 side toward the developer containing tank 111 side. The function can suppress clogging of toner inside the toner transfer tube 200.

  In addition, since the drive belt 201 extends in the toner transfer pipe 200 along the toner transfer direction and moves in the toner transfer direction, the drive belt 201 itself is a wall surface of the toner transfer path. It can be considered that it constitutes a part of

  Further, since the drive belt 201 that is circulated is arranged on the return side outside the toner transfer tube 200 and moves only in the toner transfer direction in the toner transfer tube 200, the toner is more reliably transferred by free fall. Can assist and promote.

  Further, in order to provide such a drive belt 201 for circulation driving, only a belt member and a roller member are sufficient, and no complicated mechanism is required, and the above-described transfer assisting member can be realized with a simple configuration, low cost, and space saving. .

  Further, in the above configuration, the surface of the drive belt 201 is formed in a concavo-convex shape, but it is not necessarily required to be formed in a concavo-convex shape and may be smooth.

  Even if the surface of the driving belt 201 is smooth, when the toner moving due to free fall comes into contact with or approaches the driving belt 201, the moving force of the driving belt 201 assists and accelerates the contact and transfer of the adjacent toner. This is because toner retention can be suppressed.

  However, when the surface of the drive belt 201 is formed to be uneven, the toner transfer can be further assisted and promoted more than the configuration in which the surface of the drive belt 201 is smoothed because of the scraping action of the protrusions. Stagnation can be suppressed.

  Furthermore, in the above configuration, the drive belt 201 is used as the above-described transfer assisting member, but the transfer assisting member need not be the drive belt 201.

  For example, instead of the drive belt 201, a string-like member having both ends connected in a ring shape is stretched around the outer periphery of the driven rollers 203a and 203b and the drive roller 202, and the string-like member is circulated and driven. Conceivable.

  In this configuration, the string-like member is moved in the toner transfer tube 200 in the direction of transfer of the freely falling toner. The moving force of the string-like member also assists and promotes the transfer of the toner by the free fall. Because it can be done.

  Further, even when such a string-like member is configured, a complicated mechanism is not required, and the above-described transfer assisting member can be realized with a simple configuration, low cost, and space saving.

  Further, according to the configuration described above, the toner transfer pipe 200 is a transfer path for transferring the toner of the toner hopper 101 to the developer storage tank 111 of the developing device 103, but at a certain place (toner sending side). The toner transfer path for transferring the toner in the toner to another place (toner receiving side) by free fall may be used, and the toner hopper 101 and the developer storage tank 111 need not be in communication with each other. It does not need to be configured.

  Further, according to the above configuration, the toner transfer pipe 200 is disposed between the toner hopper 101 and the developer storage tank 111 so that the direction from the opening end 200a to the opening end 200b is parallel or substantially parallel to the vertical direction. However, it is not always necessary to be parallel or substantially parallel to the vertical direction.

  The point is that the toner transfer tube 200 may be arranged and configured to allow the toner to freely fall from the opening end 200a to the opening end 200b. For example, the direction from the opening end 200a to the opening end 200b is the horizontal direction. The toner transfer tube 200 may be arranged and inclined so as to be inclined.

  Further, the toner transfer tube 200 does not have to be linear in cross section as shown in FIG. 1, and the design of the shape may be appropriately changed as long as the drive belt 201 can be configured inside.

  Further, in the configuration of FIG. 1, the driving belt 201 returning from the developing device 103 side (downstream side) to the toner hopper 101 side (upstream side) via the driving roller 202 is outside the toner transfer pipe 200. It is arranged.

  For this reason, the toner adhering to the surface of the drive belt 201 inside the toner transfer tube 200 may be conveyed to the outside of the toner transfer tube 200 by the drive belt 201.

  Here, when the toner adhering to the driving belt 201 falls from the driving belt 201 outside the toner transfer tube 200, there arises a disadvantage that the toner is scattered outside the developing unit 2.

  Therefore, in order to eliminate such inconvenience, as shown in FIG. 3, a cover member that covers the through holes 200c and 200d, the driven rollers 203a and 203b, the driving roller 202, and the driving belt 201 on the outer wall of the toner transfer tube 200. 300 may be provided.

  According to this configuration, since the cover member 300 is covered around the drive belt 201 returning from the developer storage tank 111 side to the toner hopper 101 side via the drive roller 202, the drive belt 201 The falling toner is received by the cover member 300, and the situation where the toner is scattered outside the developing unit 2 can be suppressed.

  Further, as shown in FIG. 4, the inner wall surface of the toner transfer tube 200 is recessed to form a recess 200e, and the driven rollers 203a and 203b, the driving roller 202, and the driving belt 201 are arranged in the recess 200e. It is possible to avoid the situation where the toner falling from the driving belt 201 is scattered outside the developing unit 2. In this case, a toner transfer path is secured by the inner wall of the toner transfer pipe 200 other than the recess 200e and the surface of the drive belt 201 moving in the direction from the toner hopper 101 side to the developer storage tank 111 side. The Rukoto.

  Furthermore, the driving roller 202 that drives the driving belt 201 and the toner supply roller 110 in the toner hopper 101 may be driven by the same driving source.

  As a result, one drive source can be omitted, and the space of the image forming apparatus can be further reduced.

  For example, as shown in FIG. 4, a first gear (driving force transmission means) 310 sharing a shaft with the toner supply roller 110 and a second gear (driving force transmission means) 311 sharing a shaft with the driving roller 202 are provided. Constitute. Furthermore, a third gear (driving force transmission means) 312 that meshes with the first gear 310 and the second gear 311 is configured.

  In this way, a driving force can be transmitted between the toner replenishing roller 110 and the driving roller 202. Therefore, if a driving force from a driving source is applied to either the toner replenishing roller 110 or the driving roller 202, Both rollers 110 and 202 can be driven to rotate, and the driving source of both rollers 110 and 202 can be the same.

  For example, when the shaft of the toner supply roller 110 is driven by the driving force from the drive source, the toner supply roller 110 and the first gear 310 rotate in the same direction, and the rotation of the first gear 310 causes the third gear 312 to rotate. The first gear 310 rotates in the opposite direction. When the third gear 312 rotates, the second gear 311 rotates in the opposite direction to the third gear 312, and the drive roller 202 can be rotated according to the rotation of the second gear 311.

  Similarly, the driving roller 202 and the stirring roller 112a or 112b may be driven by the same driving source, and the driving roller 202 and the developing roller 114 may be driven by the same driving source.

  In the developing device 103 described above, the stirring rollers 112a and 112b in the developer containing tank 111 stir the toner, generate static electricity by friction between the toners, and charge the toner. The toner can be charged also by providing a bias roller (charging roller) instead of 112a and 112b.

  In this embodiment, a developing device storing a two-component developer is assumed. However, the developer does not necessarily need to be a two-component developer. A developer composed only of toner may be used. However, in the case of using a one-component developer or a developer made of magnetic toner, it is necessary to change the design of the developing roller 114 in the developing device 103 to a conductive elastic roller instead of a magnet roller.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and the embodiments can be obtained by appropriately combining the respective technical means disclosed in the above-described embodiments. The form is also included in the technical scope of the present invention.

  The toner transfer mechanism, developing unit, and image forming apparatus of the present invention are suitable for electrophotographic printers, copiers, facsimiles, multifunction machines, and the like.

FIG. 3 is a longitudinal sectional view showing a developing unit including a toner transfer mechanism according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing an image forming apparatus provided with the developing unit shown in FIG. 1. FIG. 6 is a longitudinal sectional view showing a developing unit including a toner transfer mechanism according to another embodiment of the present invention. FIG. 10 is a longitudinal sectional view showing a developing unit including a toner transfer mechanism according to still another embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the inside of a developer storage tank that is a component of the developing unit of FIG.

Explanation of symbols

2 Developing Unit 3 Photosensitive Drum 101 Toner Hopper 101a Toner Delivery Port 102 Toner Transfer Mechanism 103 Developing Device 110 Toner Supply Roller 111 Developer Storage Tank 111a Toner Inlet 111b Partition Plates 112a and 112b Stirring Roller 114 Developing Roller 115 Blade 200 Toner Transfer Tube (toner transfer path)
200a / 200b Open end 200c / 200d Through hole 200e Recess 201 Drive belt (transfer assisting member, circulation driving member, belt member)
202 Drive roller 203a / 203b Driven roller 300 Cover member 310 First gear 311 Second gear 312 Third gear

Claims (6)

A toner transfer path for transferring toner by free fall from the toner delivery side to the toner reception side;
A transfer auxiliary member provided in the toner transfer path and assisting in transferring the toner by moving in the toner transfer direction ;
The transfer auxiliary member is a circulation drive member that moves with the toner delivery side as an upstream and the toner reception side as a downstream in the toner transfer path, and returns from the downstream to the upstream outside the toner transfer path,
The toner transfer mechanism, wherein the circulation drive member is a string-like member . The toner transfer mechanism according to claim 1 ,
A toner transfer mechanism comprising a cover member that covers the return side of the circulation drive member. A toner hopper for storing toner;
A developing device that replenishes toner from the toner hopper and supplies the toner to the photoreceptor;
A toner transfer path that communicates the toner hopper with the developing device, and transfers toner from the toner hopper to the developing device by free fall;
A transfer auxiliary member that is provided in the toner transfer path and assists the transfer of the toner by moving in the toner transfer direction ;
The transfer auxiliary member is a circulation drive member that moves with the toner hopper side as the upstream and the developing device side as the downstream in the toner transfer path, and returns from the downstream to the upstream outside the toner transfer path,
The developing unit of an image forming apparatus, wherein the circulation driving member is a string member . The developing unit according to claim 3 ,
A toner supply roller for feeding the toner from the toner hopper to the toner transport path,
A drive roller for driving the circulation drive member,
The developing unit, wherein the toner supply roller and the driving roller are given driving force from the same driving source. An image forming apparatus comprising the toner transfer mechanism according to claim 1 . An image forming apparatus comprising the developing unit according to claim 3 .

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