JP5165493B2 - Developing device and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus using the same, and more particularly to an image forming apparatus such as an electrostatic copying machine, a laser printer, and a facsimile machine that forms an image using toner by an electrophotographic method. The present invention relates to a developing device using a two-component developer containing a magnetic carrier and an image forming apparatus using the developing device.

  2. Description of the Related Art Conventionally, electrophotographic image forming apparatuses such as copying machines, printers, and facsimiles are known. An electrophotographic image forming apparatus forms an electrostatic latent image on the surface of a photosensitive drum (toner image carrier), and develops the electrostatic latent image by supplying toner to the photosensitive drum by a developing device. The toner image formed on the photosensitive drum by development is transferred to a sheet such as paper, and the toner image is fixed on the sheet by a fixing device.

  2. Description of the Related Art In recent years, two-component developers (hereinafter simply referred to as “developers”) that are excellent in toner charge stability are often used in image forming apparatuses that support full color and high image quality.

  This developer is composed of toner and carrier, and the toner and the carrier are rubbed by stirring them in the developing device, and a properly charged toner is obtained by this friction.

  In the developing device, the charged toner is supplied to the surface of a developer carrying member, for example, a developing roller. The toner supplied to the developing roller moves to an electrostatic latent image formed on the photosensitive drum by an electrostatic attraction force. As a result, a toner image based on the electrostatic latent image is formed on the photosensitive drum.

  Furthermore, recently, there has been a demand for speeding up and downsizing of an image forming apparatus, and it has become necessary to quickly and sufficiently charge the developer and to quickly transport the developer.

In view of this, in the image forming apparatus, a circulation type developing device is employed in order to instantly disperse the replenished toner in the developer and impart an appropriate charge amount. The circulation type developing device includes a developer conveying path that is a path through which the developer is circulated and a developer conveying member that conveys the developer while stirring the developer in the developer conveying path (Patent Document 1). See).
JP-A-9-120201

  In the above-described circulation type developing device, when the toner concentration of the developer in the developing device falls below a predetermined value, the toner is supplied from the toner hopper to the developer conveying path.

  However, since the specific gravity of the toner of the developer is considerably smaller than the specific gravity of the carrier (about 1/3), the replenished toner easily floats on the developer. When the amount of replenished toner replenished from the toner hopper to the developer conveyance path is large, there is a problem that the toner is conveyed in a lump on the developer.

  As a result, a situation has occurred in which toner that is not sufficiently mixed with the carrier (a lowly charged toner that is not sufficiently charged) is supplied to the developing roller.

  That is, if toner that is not sufficiently charged is supplied to the developing roller, the toner easily scatters from the developing roller, causing a problem that the image forming apparatus and an image formed on the sheet are stained.

  Further, if toner that is not sufficiently charged is supplied to the developer carrying member, the electrostatic force for holding the toner on the carrier surface is reduced, and the toner adheres to the non-image area and is likely to be fogged. The problem arises.

  The present invention has been made in view of the above-described conventional problems. In the developing device, toner that is not sufficiently charged is prevented from being supplied to the developing roller, thereby reducing toner scattering and image fogging. An object of the present invention is to provide a developing device capable of performing the above and an image forming apparatus using the same.

  The developing device and the image forming apparatus using the same according to the present invention for solving the above-described problems are as follows.

The present invention provides a developer containing portion for containing a developer containing toner and a magnetic carrier, a developer carrying path for carrying the developer, and the developer provided in the developer carrying path. A developer carrying member that carries the developer in a predetermined direction while stirring; a developer carrying member that carries the developer in the developer carrying path and supplies toner contained in the developer to the photosensitive drum; and the developer carrying In a developing device having a toner supply port for supplying toner to a path,
The developer transport member includes a rotation shaft and a spiral blade provided around the rotation shaft to transport the developer, and is disposed below the toner supply port.
The spiral blade has a cross-sectional shape along the axial direction of the rotation shaft of the portion facing the toner supply port, and an angle formed by the rotation shaft and the upstream side surface and the downstream side surface of the spiral blade in the developer conveying direction is the rotation shaft. The spiral blade is formed so as to have an obtuse angle, that is, the radially outer end of the spiral blade is positioned upstream of the rotating shaft side base in the developer transport direction. Is.

In the present invention, it is preferable that an angle formed between the rotating shaft and the upstream side surface and the downstream side surface of the spiral blade in the developer conveying direction is not less than 100 degrees and not more than 150 degrees with respect to the downstream side portion of the rotating shaft .

  In the present invention, the spiral blade is formed such that the spiral pitch of the portion facing the toner supply port is maximized, and the spiral pitch of the spiral blade is 0.3 times or more the maximum value of the minimum value. It is preferable to form it by 0.7 times or less.

  In the present invention, it is preferable that the spiral blade is constituted by one continuous spiral blade body.

  According to the present invention, the developer transport path includes a first transport path and a second transport path arranged side by side, and the first transport path and the second transport path have the first transport path at both ends. A first communication path and a second communication path that communicate between the first conveyance path and the second conveyance path are formed, and the developer conveyance member is provided in the first conveyance path as a configuration of the developer conveyance member. A first conveying member that conveys the developer in a predetermined direction while stirring the developer; and a developer conveying direction that is provided in the second conveying path and is stirred by the first conveying member while stirring the developer in the second conveying path; Includes a second conveying member that conveys in the opposite direction, and the developer is conveyed from the first conveying path to the second conveying path via the first communicating path, and from the second conveying path to the second communicating path. It is configured to be transported to a first transport path, and the first transport member of the developer transport member is a toner. Disposed below the feed inlet, the spiral blade, it is preferably configured to provide the first conveying member.

  The present invention also provides a photosensitive drum on which an electrostatic latent image is formed, a charging device that charges the surface of the photosensitive drum, an exposure device that forms an electrostatic latent image on the surface of the photosensitive drum, and a photosensitive member. Developing device for supplying toner to electrostatic latent image on drum surface to form toner image, toner replenishing device for replenishing toner to developing device, and transfer device for transferring toner image on photosensitive drum surface to recording medium And a fixing device that fixes the toner image on the recording medium, and forms an image using toner by an electrophotographic method, wherein the developing device is any one of claims 1 to 5. The developing device described above is used.

According to the present invention, a developer accommodating portion that accommodates a developer containing toner and a magnetic carrier, a developer conveying path for conveying the developer, and the developer provided in the developer conveying path. A developer carrying member that carries the developer in a predetermined direction while stirring the developer, a developer carrying member that carries the developer in the developer carrying path and supplies toner contained in the developer to the photosensitive drum, and the development In the developing device having a toner supply port for supplying toner to the agent transport path, the developer transport member includes a rotation shaft and a spiral blade provided around the rotation shaft to transport the developer. The spiral blade is disposed below the toner supply port, and the spiral blade has a cross-sectional shape along the axial direction of the rotation shaft of the portion facing the toner supply port, and the upstream side surface in the developer conveying direction of the rotation shaft and the spiral blade. and the angle between the downstream face As an obtuse angle with respect to the downstream portion of the serial rotation axis, i.e., that the radially outer end of the spiral vane than the rotation shaft side base portion formed so as to be located in the developer conveyance direction upstream side Since the developer pushes the developer outward by the rotation of the first conveying member, the developer is lifted upward in the vertical direction, and at the same time, a space is formed in the vicinity of the rotation shaft and is supplied from the toner supply port. As the toner flows into the space, mixing of the developer and the replenishing toner is promoted. As a result, even when there is a large amount of replenished toner, the necessary charge amount is quickly applied to the toner, so that toner scattering due to uncharged toner can be prevented.

Further, according to the present invention, the angle formed between the rotating shaft and the upstream side surface and the downstream side surface of the spiral blade in the developer conveying direction is set to 100 degrees to 150 degrees with respect to the downstream portion of the rotating shaft. As a result, the developer is lifted to the upper part in the vertical direction on the downstream side of the developer conveyance direction of the spiral blade without excessively stressing the developer, and the replenishment toner is generated by the shearing force generated between the spiral blade and the inner wall of the developer tank. Therefore, even when the replenished toner is replenished as a lump, the toner and the carrier can be quickly mixed.

  Further, according to the present invention, the spiral blade is formed so that the spiral pitch of the portion facing the toner supply port is maximized, and the spiral pitch of the spiral blade is set to a minimum value of 0.3. Since the developer transport amount is larger than the other portions in the portion facing the toner replenishing port, the developer surface becomes lower than the other in the portion facing the toner replenishing port. The replenished toner is easily taken into the developer by the rotation of the spiral blade provided in the lower portion of the toner. Therefore, even when there is a large amount of replenished toner, it is possible to prevent the replenished toner from being conveyed while floating on the developer surface, and to prevent toner scattering due to uncharged toner.

  Further, according to the present invention, since the spiral blade is constituted by one continuous spiral blade body, the developer can be smoothly conveyed in the axial direction of the rotation axis of the developer conveying member. The stress on the developer can be reduced, and the developer deterioration can be prevented.

  Further, according to the present invention, as a configuration of the developer transport path, the developer transport path includes a first transport path and a second transport path arranged in parallel, and at both ends of the first transport path and the second transport path, A first communication path and a second communication path that connect the first conveyance path and the second conveyance path are formed, and the first conveyance path is provided in the first conveyance path as a configuration of the developer conveyance member. A first conveying member that conveys the developer in the path in a predetermined direction while stirring, and a developer conveyance that is provided in the second conveying path and that is stirred by the first conveying member while stirring the developer in the second conveying path. A second conveying member that conveys in a direction opposite to the direction, and the developer is conveyed from the first conveying path to the second conveying path via the first communicating path, and from the second conveying path to the second communicating path. And the first conveying member of the developer conveying member is configured to be conveyed to the first conveying path. By arranging the spiral blade on the first conveying member, the developer circulated in the developer conveying path and the replenishing toner introduced from the toner replenishing port are arranged below the toner replenishing port. The mixing property can be improved.

  Further, according to the present invention, a photosensitive drum on which an electrostatic latent image is formed, a charging device that charges the surface of the photosensitive drum, an exposure device that forms an electrostatic latent image on the surface of the photosensitive drum, A developing device that supplies toner to the electrostatic latent image on the surface of the photosensitive drum to form a toner image, a toner replenishing device that supplies toner to the developing device, and a toner image on the surface of the photosensitive drum is transferred to a recording medium. 6. An image forming apparatus that includes a transfer device and a fixing device that fixes a toner image on a recording medium, and forms an image using toner by an electrophotographic method, and the developing device is any one of claims 1 to 5. By using the developing device described in the item, the replenishment toner can be mixed with the carrier (developer) without significantly increasing stress on the developer. As a result, the problem of toner scattering and image fogging caused by toner that is not sufficiently charged can be reduced, and a good image can be obtained.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is an example of an embodiment for carrying out the invention, and is an explanatory view showing the overall configuration of an image forming apparatus using a developing device according to an embodiment of the present invention.

  In the first embodiment, as shown in FIG. 1, a photosensitive drum 3 on which an electrostatic latent image is formed, a charger (charging device) 5 that charges the surface of the photosensitive drum 3, and the photosensitive drum 3. An exposure unit (exposure device) 1 for forming an electrostatic latent image on the surface, a developing device 2 for supplying toner to the electrostatic latent image on the surface of the photosensitive drum 3 to form a toner image, and a toner for the developing device 2 A toner hopper (toner replenishing device) 101 for replenishing, an intermediate transfer belt unit (transfer device) 8 for transferring the toner image on the surface of the photosensitive drum 3 to a recording medium, and a fixing unit (fixing device) for fixing the toner image on the recording medium. In the image forming apparatus 100 that forms an image using toner by electrophotography, the developing device 2 according to the present invention is employed as the developing device 2.

  The image forming apparatus 100 forms a multicolor or single color image on a predetermined sheet (recording paper, recording medium) according to image data transmitted from the outside. A scanner or the like may be provided above the image forming apparatus 100.

First, the overall configuration of the image forming apparatus 100 will be described.
As shown in FIG. 1, the image forming apparatus 100 handles image data for each color component of black (K), cyan (C), magenta (M), and yellow (Y), so that a black image, cyan image, magenta An image and a yellow image are formed, and a color image is formed by superimposing the images of the respective color components.

  Accordingly, in the image forming apparatus 100, as shown in FIG. 1, the developing device 2 (2a, 2b, 2c, 2d) and the photosensitive drum 3 (3a, 3b, 3c) are formed so that images of the respective color components are formed. , 3d), four chargers 5 (5a, 5b, 5c, 5d) and four cleaner units 4 (4a, 4b, 4c, 3d). In other words, four image forming stations (image forming units) each including the developing device 2, the photosensitive drum 3, the charger 5, and the cleaner unit 4 are provided.

  The symbols a to d indicate that a is a member for forming a black image, b is a member for forming a cyan image, c is a member for forming a magenta image, and d is a member for forming a yellow image. It is a thing. Further, the image forming apparatus 100 includes an exposure unit 1, a fixing unit 12, a sheet conveyance path S, a paper feed tray 10, and a paper discharge tray 15.

The charger 5 uniformly charges the surface of the photosensitive drum 3 to a predetermined potential.
As the charger 5, a contact brush type charger or a non-contact charger type charger may be used in addition to the contact roller type charger shown in FIG.

  As shown in FIG. 1, the exposure unit 1 is a laser scanning unit (LSU) including a laser irradiation unit and a reflection mirror. However, in addition to the laser scanning unit, the exposure unit 1 may be an EL (electroluminescence) in which light emitting elements are arranged in an array or an LED writing head. The exposure unit 1 exposes the charged photosensitive drum 3 according to the input image data, thereby forming an electrostatic latent image corresponding to the image data on the surface of the photosensitive drum 3.

  The developing device 2 visualizes (develops) the electrostatic latent image formed on the photosensitive drum 3 with one of K, C, M, and Y toners. The developing device 2 (2a, 2b, 2c, 2d) includes a toner hopper 101 (101a, 101b, 101c, 101d), a toner transfer mechanism 102 (102a, 102b, 102c, 102d), and a developing tank (developer container) 111. (111a, 111b, 111c, 111d).

  The toner hopper 101 is arranged on the H direction side of the developing tank 111 and stores unused toner (powder toner). The toner is supplied from the toner hopper 101 to the developing tank 111 via the toner transfer mechanism 102.

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

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

  The intermediate transfer belt 6, the intermediate transfer belt drive roller 71, the intermediate transfer belt driven roller 72, and the intermediate transfer belt tension mechanism 73 stretch the intermediate transfer belt 7 and rotationally drive the intermediate transfer belt 7 in the direction of arrow B in FIG. It is something to be made.

  The intermediate transfer roller 6 is rotatably supported by an intermediate transfer roller mounting portion in the intermediate transfer belt tension mechanism 73 of the intermediate transfer belt unit 8. A transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 7 is applied to the intermediate transfer roller 6.

  The intermediate transfer belt 7 is provided so as to be in contact with each photosensitive drum 3. A color toner image (multicolor toner image) is formed on the intermediate transfer belt 7 by sequentially superimposing and transferring the toner images of the respective color components formed on the photosensitive drum 3. The intermediate transfer belt 7 is formed in an endless shape using a film having a thickness of, for example, 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. A high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image.

  The intermediate transfer roller 6 is formed based on a metal (for example, stainless steel) shaft having a diameter of, for example, 8 to 10 mm, and the surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, the intermediate transfer roller 6 can uniformly apply a high voltage to the intermediate transfer belt 7. In this embodiment, a roller-shaped transfer electrode (intermediate transfer roller 6) is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the electrostatic latent images on the respective photosensitive drums 3 are visualized with toners corresponding to the respective color components to become toner images, and these toner images are superimposed and laminated on the intermediate transfer belt 7. As described above, the stacked toner images are moved to a contact position (transfer portion) between the conveyed paper and the intermediate transfer belt 7 by the rotation of the intermediate transfer belt 7, and the transfer roller disposed at this position is moved. 11 is transferred onto the paper. In this case, the intermediate transfer belt 7 and the transfer roller 11 are pressed against each other at a predetermined nip, and a voltage for transferring the toner image onto the sheet is applied to the transfer roller 11. This voltage is a high voltage having a polarity (+) opposite to the charging polarity (−) of the toner.

  In order to obtain the nip constantly, either the transfer roller 11 or the intermediate transfer belt drive roller 71 is made of a hard material such as metal, and the other is a soft material such as an elastic roller (elastic rubber roller or foamable resin roller). Etc.).

  The toner adhering to the intermediate transfer belt 7 due to the contact between the intermediate transfer belt 7 and the photosensitive drum 3 and the toner image remaining on the intermediate transfer belt 7 without being transferred when the toner image is transferred from the intermediate transfer belt 7 to the sheet. The toner is removed and collected by the intermediate transfer belt cleaning unit 9 because it causes toner color mixing in the next step.

  The intermediate transfer belt cleaning unit 9 is provided with a cleaning blade (cleaning member) that contacts the intermediate transfer belt 7. The portion of the intermediate transfer belt 7 that is in contact with the cleaning blade is supported by the intermediate transfer belt driven roller 72 from the back side.

  The paper feed tray 10 is for storing sheets (for example, recording paper) used for image formation, and is provided below the image forming unit and the exposure unit 1. On the other hand, a paper discharge tray 15 provided in the upper part of the image forming apparatus 100 is for placing printed sheets face down.

  Further, the image forming apparatus 100 is provided with a sheet conveyance path S for guiding the sheet of the paper feed tray 10 and the sheet of the manual feed tray 20 to the paper discharge tray 15 via the transfer unit and the fixing unit 12. . The transfer unit is located between the intermediate transfer belt driving roller 71 and the transfer roller 11.

  Further, a pickup roller 16 (16a, 16b), a registration roller 14, a transfer unit, a fixing unit 12, a conveyance roller 25 (25a to 25h), and the like are arranged in the sheet conveyance path S.

  The conveyance rollers 25 are 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 pull-in roller that is provided at the end of the paper feed tray 10 and supplies sheets one by one from the paper feed tray 10 to the sheet conveyance path S. The pickup roller 16 b is a drawing roller that is provided near the manual feed tray 20 and supplies sheets from the manual feed tray 20 to the sheet conveyance path S one by one. The registration roller 14 temporarily holds the sheet conveyed in the sheet conveyance path S, and conveys the sheet to the transfer unit at a timing when the leading edge of the toner image on the intermediate transfer belt 7 and the leading edge of the sheet are aligned.

  The fixing unit 12 includes a heat roller 81, a pressure roller 82, and the like. The heat roller 81 and the pressure roller 82 rotate with the sheet interposed therebetween. The heat roller 81 is controlled by a control unit (not shown) so as to have a predetermined fixing temperature. This control unit controls the temperature of the heat roller 81 based on a detection signal from a temperature detector (not shown).

  The heat roller 81 heat-presses the sheet together with the pressure roller 82 to melt, mix, and press the color toner images transferred to the sheet, and heat-fix the sheet. The sheet on which the multicolor toner image (each color toner image) is fixed is conveyed to the reverse sheet discharge path of the sheet conveyance path S by the plurality of conveyance rollers 25 and is reversed (the multicolor toner image is on the lower side). Are discharged onto the paper discharge tray 15.

Next, the sheet conveying operation by the sheet conveying path S will be described.
As shown in FIG. 1, the image forming apparatus 100 is provided with a paper feed tray 10 that stores sheets in advance and a manual feed tray 20 that is used when printing a small number of sheets as described above. Pickup rollers 16 (16a, 16b) are disposed on both trays, and the pickup rollers 16 supply sheets one by one to the sheet conveyance path S.

  In the case of single-sided printing, the sheet conveyed from the sheet feeding tray 10 is conveyed to the registration roller 14 by the conveyance roller 25a in the sheet conveyance path S, and is stacked on the leading edge of the sheet and the intermediate transfer belt 7 by the registration roller 14. Then, the toner image is conveyed to a transfer portion (contact position between the transfer roller 11 and the intermediate transfer belt 7) at a timing when the leading edge of the toner image is aligned. In the transfer portion, a toner image is transferred onto the sheet, and this toner image is fixed on the sheet by the fixing unit 12. Thereafter, the sheet is discharged onto the discharge tray 15 from the discharge roller 25c via the conveyance roller 25b.

  Further, the sheet conveyed from the manual feed tray 20 is conveyed to the registration roller 14 by a plurality of conveying rollers 25 (25f, 25e, 25d). Subsequent sheet conveyance operations are discharged to the sheet discharge tray 15 through a process similar to that for the sheets supplied from the sheet feed tray 10 described above.

  On the other hand, in the case of double-sided printing, the trailing edge of the sheet that has completed single-sided printing and passed through the fixing unit 12 as described above is chucked by the paper discharge roller 25c. Next, the sheet is guided to the conveying rollers 25g and 25h by the reverse rotation of the paper discharge roller 25c, and after the printing on the back surface is again performed through the registration roller 14, it is discharged to the paper discharge tray 15.

Next, the characteristic developing device 2 of the first embodiment will be described with reference to the drawings.
2 is a cross-sectional view showing the configuration of the developing device constituting the image forming apparatus according to the first embodiment, FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 4 is a cross-sectional view taken along the line BB in FIG. FIG. 5 and FIG. 5 are cross-sectional views showing the configuration of the first conveying member constituting the developing device in FIG.

  As shown in FIG. 2, the developing device 2 has a developing roller (developer carrying member) 114 disposed in the developing tank 111 so as to face the photosensitive drum 3. 3 is a device for supplying (developing) an electrostatic latent image formed on the surface of the photosensitive drum 3 by supplying toner to the surface of the photosensitive drum 3.

  In addition to the developing roller 114, the developing device 2 includes a developing tank 111, a developing tank cover 115, a toner supply port 117, a doctor blade 116, a first conveying member 112a, a second conveying member 112b, and a partition plate (partition wall) 113. I have.

  The developing tank 111 is a tank that stores a developer containing toner and a carrier. The developing tank 111 is provided with a developing roller 114, a first conveying member 112a, a second conveying member 112b, and the like. Note that the carrier of this embodiment is a magnetic carrier having magnetism.

  The developing roller 114 is a rotating magnet roller that pumps and carries the developer in the developing tank 111 on the surface and supplies toner contained in the developer carried on the surface to the photosensitive drum 3. A doctor blade (layer thickness regulating blade) 116 is disposed at a position close to the surface of the developing roller 114.

  Further, as shown in FIGS. 2 and 4, a detachable developing tank cover 115 is provided above the developing tank 111. Further, as shown in FIG. 4, the developer tank cover 115 is provided with a toner supply port 117 for supplying unused toner to the developer tank 111.

  As shown in FIG. 1, the toner accommodated in the toner hopper 101 is transferred to the developing tank 111 through the toner transfer mechanism 102 and the toner supply port 117, and thereby the toner is supplied to the developing tank 111. It is like that.

  Further, as shown in FIG. 2 to FIG. 5, the first transport member 112 a and the second transport member 112 b are provided with the rotation shafts 112 a 1 and 112 b 1 and a spiral transport for stirring and transporting the developer in the developing tank 111. It is constituted by a screw auger composed of blades (spiral blades) 112a2 and 112b2, and the rotation shafts 112a1 and 112b1 are rotationally driven by driving means (not shown) such as a motor so that the developer is stirred and conveyed. It has become.

  The first transport member 112a and the second transport member 112b are arranged in parallel so that their peripheral surfaces face each other via the partition plate 113 and their axes are parallel to each other, and rotate in opposite directions. Is set to Then, as shown in FIG. 3, the first transport member 112a transports the developer in the arrow X direction, and the second transport member 112b transports the developer in the arrow Y direction opposite to the arrow X direction. Is set to

  In the developing tank 111, a partition plate 113 is disposed between the first transport member 112a and the second transport member 112b. The partition plate 113 extends in parallel with each axial direction (each rotational axis direction) of the first transport member 112a and the second transport member 112b. The interior of the developing tank 111 is partitioned by a partition plate 113 into a first transport path P in which the first transport member 112a is disposed and a second transport path Q in which the second transport member 112b is disposed.

  The partition plate 113 is disposed away from the inner wall surface of the developing tank 111 at both axial ends of the first transport member 112a and the second transport member 112b. As a result, in the developing tank 111, a communication path that connects the first transport path P and the second transport path Q is formed in the vicinity of both axial ends of the first transport member 112a and the second transport member 112b. ing. Hereinafter, as illustrated in FIG. 4, the communication path formed on the arrow X direction side is referred to as a first communication path a, and the communication path formed on the arrow Y direction side is referred to as a second communication path b.

  As shown in FIGS. 4 and 5, the first transport member 112 a includes a rotation shaft 112 a 1 and a spiral blade 112 a 2. The spiral blade 112a2 includes spiral blades 112a21 and 112a22 having different shapes.

  As shown in FIG. 5, the spiral blade 112a21 is a spiral conveying blade provided so as to be perpendicular to the rotation shaft 112a1 in a sectional view along the axial direction of the rotation shaft 112a1.

  As shown in FIG. 5, the spiral blade 112a22 has a radially outer end 112a22a of the spiral blade 112a22 in the developer conveyance direction (arrow X) as compared to the rotation shaft side base 112a22b in a cross-sectional view along the axial direction of the rotation shaft 112a1. Direction) A spiral conveying blade formed so as to be located on the upstream side and provided so that the angle θ formed with the rotation shaft 112a1 becomes an obtuse angle on the downstream side in the developer conveying direction.

  In the present embodiment, in the first conveying member 112a, the maximum value of the angle θ formed by the rotation shaft 112a1 and the spiral blade 112a22 is 135 degrees, and the spiral blade 112a22 is located below the toner supply port 117. It is arranged at a position facing 117.

  The spiral pitch (the length in the rotation axis direction when the spiral blade makes one round around the rotation axis) P2 in the spiral blade 112a22 is formed larger (longer) than the spiral pitch P1 in the spiral blade 112a21, and the spiral blade 112a21 and the spiral blade 112a22 is formed as one continuous spiral blade.

  In the present embodiment, as shown in FIG. 5, the spiral blade 112a2 of the first transport member 112a has a spiral pitch P1 of the spiral blade 112a21 having a short spiral pitch of 0. 0 of the spiral pitch P2 of the spiral blade 112a22 having a long spiral pitch. It is formed to be 67 times.

  That is, by setting the spiral pitch P2 of the spiral blade 112a22 located below the toner supply port 117 to be longer than the spiral pitch P1 of the other spiral blade 112a21, the rotation shaft 112a1 rotates when the first transport member 112a rotates once. Since the amount of developer conveyed along the axial direction is greater than that of other portions (portions with a short helical pitch), the developer surface below the toner supply port 117 is lower than the other portions. As a result, the replenished toner that is replenished from the toner replenishing port 117 and stirred and conveyed by the spiral blade 112a22 is more efficiently mixed with the developer.

  As shown in FIG. 3, the second transport member 112b includes a rotating shaft 112b1 and a spiral blade 112b2 formed at a spiral pitch P1.

  In the present embodiment, the toner supply port 117 is an area in the first transport path P and is formed at a position on the arrow X direction side of the second communication path b. That is, in the first transport path P, the toner is replenished downstream of the second communication path b.

In the developing tank 111, the first transport member 112a and the second transport member 112b are rotationally driven by a driving unit (not shown) such as a motor to transport the developer.
Specifically, in the first transport path P, the developer is transported in the direction of the arrow X while being stirred by the first transport member 112a, and reaches the first communication path a. The developer that has reached the first communication path a passes through the first communication path a and is conveyed to the second conveyance path Q.

  On the other hand, in the second transport path Q, the developer is transported in the direction of the arrow Y while being stirred by the second transport member 112b and reaches the second communication path b. Then, the developer that has reached the second communication path b passes through the second communication path b and is conveyed to the first conveyance path P. That is, the first transport member 112a and the second transport member 112b transport the developer in the opposite directions while stirring the developer.

  In this way, the developer passes through the first conveyance path P, the first communication path a, the second conveyance path Q, and the second communication path b in the developing tank 111 from the first conveyance path P to the first communication path. Circulating movement is performed in the order of a → second conveyance path Q → second communication path b. Then, while the developer is being conveyed in the second conveyance path Q, the developer is carried on the surface by the rotation of the developing roller 114 and pumped up, and the toner in the developer that has been pumped up is transferred to the photosensitive drum 3. It moves and is consumed sequentially.

  In order to supplement the consumed toner, unused toner is replenished from the toner replenishing port 117 to the first transport path P. The replenished toner is mixed and agitated with the developer existing in the first conveyance path P.

Here, the mixing and stirring action of the replenishing toner T and the developer D in the developing tank 111 of the developing device 2 according to the present embodiment will be described with reference to the drawings.
FIG. 6 is an explanatory diagram showing a state where toner replenished in the developing device of the image forming apparatus according to the present embodiment is mixed with the developer.

  In the developing device 2 of the present embodiment, as shown in FIGS. 5 and 6, the angle θ formed by the spiral blade 112a22 of the first conveying member 112a and the rotating shaft 112a1 is formed at 135 degrees on the downstream side in the developer conveying direction. As a result, when the first conveying member 112a rotates, a force for pushing the developer D to the outside of the rotating shaft 112a1 (outside in the rotational radius direction) acts on the spiral blade 112a22. As a result, as shown in FIG. 6, the developer D1 is lifted upward in the vertical direction and a space D2 is formed in the vicinity of the rotating shaft 112a1 at the portion facing the toner supply port 117 in the developing tank 111. It becomes a state.

  In this state, the toner (supplementary toner) T replenished from the toner replenishing port 117 flows into the space D2 of the developer D and is mixed with the developer D by the rotation of the spiral blade 112a22, as shown in FIG. Further, since the spiral blade 112a2 presses the developer D against the inner wall side of the developing tank 111, a shearing force for pulverizing the developer D is generated, so that the replenishment toner T is easily crushed.

  With the above configuration, according to the present embodiment, the angle θ formed by the spiral blade 112a22 of the first transport member 112a and the rotation shaft 112a1 is formed at 135 degrees on the downstream side in the developer transport direction. The effect of taking the replenishment toner T into the developer D can be improved, and the crushing effect of the replenishment toner T can be improved. As a result, the toner T replenished in the developing tank 111 is sufficiently stirred with the developer (carrier) D, and a necessary charge amount can be quickly obtained.

  Therefore, according to the present embodiment, even when the amount of the replenishment toner is large, the replenishment toner T is prevented from being conveyed while being floated on the developer surface, and the developer D and the replenishment toner T are sufficiently supplied. Since the necessary charge amount can be obtained by stirring the toner, toner scattering due to uncharged toner can be prevented.

  In the present embodiment, the angle θ formed by the spiral blade 112a22 and the rotation shaft 112a1 is 135 degrees. However, when the maximum value of the angle θ is less than 100 degrees, the developer D is applied upward in the vertical direction. Since the lifting force and the force pressing the developer D against the inner wall side of the developing tank 111 are weakened, a sufficient mixing effect may not be obtained. If the angle θ exceeds 150 degrees, the stress on the developer D increases and the toner D tends to deteriorate, and the replenishment toner T tends to stay in the space D2 formed in the vicinity of the rotation shaft 112a1. The conveyance speed may be reduced.

  Further, according to the present embodiment, the first conveying member 112a is rotated once by making the spiral pitch P2 of the spiral blade 112a22 facing below the toner supply port 117 larger than the spiral pitch P1 of the other spiral blade 112a21. Since the amount of developer conveyed along the axial direction of the rotating shaft 112a1 is larger than that of the other spiral blades 112a21, the developer surface below the toner supply port 117 becomes lower than the other portions. This prevents the replenished toner T from being conveyed while being floated on the developer D, and can be reliably mixed with the developer D by the rotation of the spiral blade 112a2.

  In the above-described embodiment, the example in which the developing device 2 according to the present invention is applied to the image forming apparatus 100 as illustrated in FIG. 1 has been described. However, an image for supplying toner to the developing device 2 using the toner hopper 101 is described. The forming apparatus is not limited to the image forming apparatus and the copying machine having the above-described configuration, and can be developed to other image forming apparatuses.

  As described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope not departing from the gist of the present invention are also included in the technical scope of the present invention.

1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus in which a developing device according to a first embodiment of the present invention is used. FIG. 2 is a cross-sectional view illustrating a configuration of a developing device that constitutes the image forming apparatus. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. It is a BB cross-sectional arrow view of FIG. FIG. 5 is a cross-sectional view illustrating a configuration of a first transport member that configures the developing device in FIG. 4. FIG. 6 is an explanatory diagram illustrating a state where toner replenished in the developing device is mixed with a developer.

Explanation of symbols

1 Exposure unit (exposure equipment)
2 Developing device 3 Photosensitive drum 5 Charger (charging device)
8 Intermediate transfer belt unit (transfer device)
12 Fixing unit (fixing device)
100 Image forming apparatus 101 Toner hopper (toner supply device)
111 Developer tank (developer container)
112a First conveying member (developer conveying member)
112a1, 112b1 Rotating shaft 112a2, 112a21, 112a22, 112b2 Spiral blade 112a22a Radial outer end 112a22b Rotating shaft side base 112b Second conveying member (developer conveying member)
113 Partition (partition wall)
114 Developing roller (developer carrying member)
117 toner supply port a first communication path b second communication path D, D1 developer D2 space P first transport path (developer transport path)
P1, P2 Spiral pitch Q Second transport path (developer transport path)
T Refill toner

Claims (6)

A developer containing portion for containing a developer containing toner and a magnetic carrier; a developer carrying path for carrying the developer; and a predetermined position while stirring the developer provided in the developer carrying path A developer conveying member that conveys the toner in a direction, a developer carrying member that carries the developer in the developer conveying path and supplies toner contained in the developer to the photosensitive drum, and a toner in the developer conveying path. In a developing device having a toner replenishing port for replenishment,
The developer transport member includes a rotation shaft and a spiral blade provided around the rotation shaft to transport the developer, and is disposed below the toner supply port.
The spiral blade has a cross-sectional shape along the axial direction of the rotation shaft of the portion facing the toner supply port, and an angle formed by the rotation shaft and the upstream side surface and the downstream side surface of the spiral blade in the developer conveying direction is the rotation shaft. A developing device characterized in that the developing device is formed to have an obtuse angle with respect to the downstream side portion . 2. The angle formed by the rotating shaft and the upstream side surface and the downstream side surface in the developer conveying direction of the spiral blade is 100 degrees or more and 150 degrees or less with respect to the downstream side portion of the rotating shaft. Development device. The spiral blade is formed with the largest spiral pitch of the portion facing the toner supply port,
3. The developing device according to claim 1, wherein the spiral pitch of the spiral blade is formed such that a minimum value is not less than 0.3 times and not more than 0.7 times a maximum value.   The developing device according to claim 1, wherein the spiral blade is configured by a single continuous spiral blade body. The developer transport path has a first transport path and a second transport path arranged in parallel,
A first communication path and a second communication path that connect the first transport path and the second transport path are formed at both ends of the first transport path and the second transport path,
The developer conveying member is provided in the first conveying path, and is provided in the second conveying path, and a first conveying member that conveys the developer in the first conveying path in a predetermined direction while stirring. A second transport member that transports in a direction opposite to the developer transport direction by the first transport member while stirring the developer in the second transport path;
The developer is transported from the first transport path to the second transport path via the first communication path, and is transported from the second transport path to the first transport path via the second communication path,
The first conveying member of the developer conveying member is disposed below the toner supply port;
The developing device according to claim 1, wherein the spiral blade is provided on the first conveying member. A photosensitive drum on which an electrostatic latent image is formed, a charging device for charging the surface of the photosensitive drum, an exposure device for forming an electrostatic latent image on the surface of the photosensitive drum, and an electrostatic latent image on the surface of the photosensitive drum A developing device that supplies toner to an image to form a toner image, a toner replenishing device that replenishes toner to the developing device, a transfer device that transfers the toner image on the surface of the photosensitive drum to a recording medium, and a toner image recording In an image forming apparatus comprising a fixing device for fixing to a medium and forming an image using toner by an electrophotographic method,
An image forming apparatus using the developing device according to claim 1 as the developing device.

Images