JP2010160253A - Developing device and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device that aims improved conveying performance for a developer by suppressing accumulation of the developer in a developer-conveying path in the developing device and an image forming device using the same. <P>SOLUTION: The developing device 2 includes a developing tank 111 containing the developer, a first conveying path P and a second conveying path Q by which the developer is conveyed, a first conveying member 112 and a second conveying member 113 disposed in the first conveying path P and the second conveying path Q to convey the developer while stirring, a developing roller 114, and a toner supply port 115a to supply toner to the first conveying path P. The first conveying path P and the second conveying path Q are configured so that a base P2 at the edge of the first conveying path P downstream in the developer-conveying direction is higher than a base Q1 at the edge of the second conveying path Q upstream in the developer-conveying direction. The first conveying path P and the first conveying member 112 are obliquely disposed so that the downstream is higher than the upstream in the developer-conveying direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

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-10-63081

  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, when the developer in the developer tank is circulated and conveyed while stirring, the developer is clogged and stays on the downstream side of the developer conveyance path. If such a state continues for a long period of time with respect to the developer, the toner fluidity improver (external additive) is buried in the toner surface, the developer fluidity is extremely lowered, and the developer is difficult to transport. Occurs. As a result, there is a problem that the required developer is not supplied to the surface of the photosensitive drum and the image density is lowered.

  The present invention has been made in view of the above-described conventional problems, and a developing device that suppresses the retention of developer in the developer transport path of the developing device and improves developer transportability, and the development device. An object is to provide an image forming apparatus to be used.

  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.

  According to the present invention, a developer accommodating portion that accommodates a developer containing toner and a magnetic carrier, a first conveying path and a second conveying passage that are partitioned by a partition wall in the developer accommodating portion and communicated at both ends of the partition wall. A first conveying member that is provided in the conveying path and in the first conveying path and the second conveying path and circulates and conveys the developer in the first conveying path and the second conveying path in opposite directions. And a second conveying member, a developer carrying member (for example, a developing roller) that carries the developer in the second carrying path and supplies toner contained in the developer to the photosensitive drum, and the first carrying In a developing device having a toner replenishing port for introducing replenished toner into the path, the first transport path and the second transport path are connected to the bottom surface of the downstream end of the first transport path in the developer transport direction. Is upstream of the developer conveying direction of the second conveying path The first conveyance path and the first conveyance member are provided so as to be inclined so that the downstream side in the developer conveyance direction is higher than the upstream side. Is.

  The toner replenishing port is preferably provided upstream of the central portion of the first transport path in the developer transport direction.

  In the present invention, it is preferable that the second transport path and the developer carrying member are provided substantially horizontally, and only the first transport path is inclined.

  According to the present invention, as a configuration of the first transport path and the second transport path, a bottom surface of an end portion of the second transport path on the downstream side in the developer transport direction is defined as a developer transport direction of the first transport path. It is preferable to make it higher than the bottom surface of the upstream end.

  In addition, the present invention provides a screw auger that includes a rotating shaft and a spiral blade body that is formed so as to protrude in a direction perpendicular to the axial direction of the rotating shaft as the configuration of the first conveying member and the second conveying member. It is preferable that the pitch of the blades is made longer on the upstream side in the developer transport direction than on the downstream side in the developer transport direction.

  Further, the present invention provides an altitude difference between a bottom surface of an end portion of the first conveyance path on the downstream side in the developer conveyance direction and a bottom surface of an end portion of the second conveyance path on the upstream side in the developer conveyance direction. 2 It is preferable that the outer diameter of the conveying member be 0.3 times or more and 1.1 times or less.

  In addition, the present invention provides an altitude difference between a bottom surface of an end portion on the downstream side in the developer conveyance direction of the second conveyance path and a bottom surface of an end portion on the upstream side in the developer conveyance direction of the first conveyance path. It is preferable that the outer diameter of one transport member be 0.3 times or more and 1.1 times or less.

  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. A developing device for supplying toner to the electrostatic latent image on the drum surface to form a toner image, a transfer device for transferring the toner image on the surface of the photosensitive drum to a recording medium, and fixing the transferred toner image on the recording medium A developing device according to any one of claims 1 to 6 is used as the developing device in an image forming apparatus that forms an image using toner by an electrophotographic method. It is a feature.

  According to the present invention, a developer accommodating portion that accommodates a developer containing toner and a magnetic carrier, a first conveying path that is partitioned by a partition wall in the developer accommodating portion, and communicates at both ends of the partition wall; A first transport path, and a first transport path that is provided in the first transport path and the second transport path, and circulates and transports the developer in the first transport path and the second transport path in the opposite directions. A conveying member, a second conveying member, a developer carrying member that carries the developer in the second conveying path and supplies toner contained in the developer to the photosensitive drum, and replenishment toner in the first conveying path In the developing device having a toner replenishing port for introducing the toner, the bottom surface of the first transport path and the second transport path is located at the bottom of the side end portion of the first transport path on the downstream side in the developer transport direction. Bottom surface of the upstream end of the two transport paths in the developer transport direction The first conveying path and the first conveying member are inclined so that the downstream side in the developer conveying direction is higher than the upstream side, thereby developing the first conveying path. Since the developer transported downstream in the developer transport direction can smoothly move to the upstream side in the developer transport direction of the second transport path, the developer is downstream in the developer transport direction of the first transport path. It is possible to reduce stress on the developer caused by clogging and compression on the side. As a result, it is possible to improve developer transportability by suppressing a decrease in developer fluidity caused by stress on the developer.

  According to the invention, the developer in the axial direction of the developer carrying member is provided by providing the second transport path and the developer carrying member substantially horizontally and providing only the first transport path with an inclination. Therefore, the developer supply amount in the axial direction of the developer carrying member is stabilized.

  According to the invention, as a configuration of the first transport path and the second transport path, the bottom surface of the end portion of the second transport path on the downstream side in the developer transport direction is used as the developer of the first transport path. By making it higher than the bottom surface of the end portion on the upstream side in the transport direction, the developer transported to the downstream side in the developer transport direction of the second transport path can be smoothly moved upstream in the developer transport direction on the first transport path. Therefore, it is possible to reduce stress on the developer caused by clogging and compression of the developer on the downstream side in the developer conveyance direction of the second conveyance path.

  In addition, according to the present invention, as the configuration of the first transport member and the second transport member, a rotating shaft and a spiral blade body that is formed to project in a direction perpendicular to the axial direction of the rotating shaft are provided. By using a screw auger, the pitch of the blades is made longer at the upstream side in the developer transport direction than at the downstream side in the developer transport direction, so that the developer transport speed in the first transport path is increased by the developer. Since the speed is higher on the upstream side than the downstream side in the transport direction, it is possible to prevent the developer from being biased to a lower position on the upstream side in the developer transport direction due to gravity. Further, since the surface of the developer below the toner supply port is lowered, the toner is likely to be mixed with the developer.

  Further, according to the present invention, the height difference between the bottom surface of the downstream end portion of the first transport path in the developer transport direction and the bottom surface of the upstream end portion of the second transport path in the developer transport direction, By setting the outer diameter of the second conveying member to not less than 0.3 times and not more than 1.1 times, the developer conveying direction downstream side of the first conveying path and the developer conveying direction upstream side of the second conveying path As a result, an appropriate level difference occurs between the first transport path and the developer flow from the first transport path to the second transport path.

  Further, according to the present invention, the height difference between the bottom surface of the downstream end portion of the second transport path in the developer transport direction and the bottom surface of the upstream end portion of the first transport path in the developer transport direction, By setting the outer diameter of the first conveying member to not less than 0.3 times and not more than 1.1 times, the developer conveying direction downstream side of the second conveying path and the developer conveying direction upstream side of the first conveying path As a result, an appropriate height difference occurs between the second transport path and the developer flow from the second transport path to the first transport path.

  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 transfer device that transfers the toner image on the surface of the photosensitive drum to a recording medium, and the transferred toner image to the recording medium A developing device according to any one of claims 1 to 6 is used as the developing device in an image forming apparatus that forms an image using toner by an electrophotographic method. As a result, the stress caused by the compression of the developer conveyed in the conveyance path of the developing device can be reduced, so that it is possible to suppress a decrease in developer fluidity due to the stress on the developer. Thereby, since the toner can be supplied stably, it is possible to realize an image forming apparatus capable of obtaining an image without fogging and image density reduction.

1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus in which a developing device according to an embodiment of the present invention is used. FIG. 2 is a cross-sectional view illustrating a schematic configuration of a toner replenishing device constituting the image forming apparatus. It is a GG cross-sectional arrow view of FIG. FIG. 2 is a cross-sectional view illustrating a configuration of a developing device that constitutes the image forming apparatus. It is an AA cross-sectional arrow view of FIG. It is a BB cross-sectional arrow view of FIG. It is CC sectional view taken on the line of FIG. FIG. 6 is a DD cross-sectional view of FIG. 5. FIG. 6 is a sectional view taken along line FF in FIG. 5. FIG. 6 is an explanatory diagram illustrating a developer conveyance state by rotation of a first conveyance member constituting the developing device. FIG. 6 is an explanatory diagram illustrating a state in which the developer transported to the downstream side in the developer transport direction of the second transport path of the developing device moves to the upstream side in the developer transport direction of the first transport path. FIG. 6 is an explanatory diagram illustrating a state in which the developer that has been transported to the downstream side in the developer transport direction of the first transport path of the developing device moves to the upstream side in the developer transport direction of the second transport path.

Hereinafter, embodiments for carrying out the present invention will be described 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 present embodiment, as shown in FIG. 1, a photosensitive drum 3 on which an electrostatic latent image is formed, a charger (charging device) 5 for charging the surface of the photosensitive drum 3, and the surface of the photosensitive drum 3 An exposure unit (exposure device) 1 that forms an electrostatic latent image on the surface, a developing device 2 that forms a toner image by supplying toner to the electrostatic latent image on the surface of the photosensitive drum 3, and a toner supply to the developing device 2 A toner replenishing device 22, 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) 12 for fixing the toner image on the recording medium. In the image forming apparatus 100 that forms an image using toner by electrophotography, the configuration of the developing device according to the present invention is adopted 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). 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, 4d). 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. Above the developing device 2 (2a, 2b, 2c, 2d), there are a toner transfer mechanism 102 (102a, 102b, 102c, 102d), a toner replenishing device 22 (22a, 22b, 22c, 22d), a developing tank (developer). (Container) 111 (111a, 111b, 111c, 111d).

  The toner replenishing device 22 is disposed above the developing tank 111 and stores unused toner (powdered toner). The toner is supplied from the toner supply device 22 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 configuration of the toner supply device 22 of the present embodiment will be specifically described.
2 is a cross-sectional view showing a schematic configuration of a toner replenishing device constituting the image forming apparatus according to the present embodiment, and FIG. 3 is a cross-sectional view taken along the line GG in FIG.

  As shown in FIG. 2, the toner supply device 22 includes a toner container 121, a toner stirring member 125, a toner discharge member 122, and a toner discharge port 123. The toner replenishing device 22 is disposed above the developing tank 111 and stores unused toner (powdered toner). The toner in the toner replenishing device 22 is supplied from the toner discharge port 123 to the developing tank 111 through the toner transfer mechanism 102 by rotating a toner discharge member (discharge screw) 122.

  The toner storage container 121 is a substantially semi-cylindrical container member having an internal space, and rotatably supports the toner stirring member 125 and the toner discharge member 122 to store the toner. The toner discharge port 123 is a substantially rectangular opening provided below the toner discharge member 122 and from the central portion in the axial direction, and is disposed at a position facing the toner transfer mechanism 102.

  The toner agitating member 125 rotates around the rotating shaft 125 a to draw up the toner in the toner container 121 and convey it to the toner discharge member 122 while agitating the toner accommodated in the toner container 121. And a toner pumping member 125b at the tip. The toner pumping member 125 b is made of a flexible polyethylene terephthalate (PET) sheet and is attached to both ends of the toner stirring member 125.

  The toner discharge member 122 supplies the toner in the toner storage container 121 to the developing tank 111 from the toner discharge port 123, and as shown in FIG. 3, a screw including a toner transport blade 122a and a toner discharge member rotating shaft 122b. The auger and the toner discharge member rotating gear 122c are included. The toner discharge member 122 is rotationally driven by a toner discharge member drive motor (not shown). The direction of the screw auger is set so that the toner is conveyed from both axial ends of the toner discharge member 122 toward the toner discharge port 123.

  A toner discharge member partition wall 124 is provided between the toner discharge member 122 and the toner stirring member 125. Accordingly, the toner pumped up by the toner stirring member 125 can hold an appropriate amount of toner around the toner discharge member 122.

  As shown in FIG. 2, the toner stirring member 125 rotates in the direction of the arrow Z, stirs the toner, and pumps the toner toward the toner discharge member 122. At this time, the toner scooping member 125b rotates and slides along the inner wall of the toner container 121 due to its flexibility, and supplies the toner to the toner discharge member 122 side. The supplied toner is guided to the toner discharge port 123 by the rotation of the toner discharge member 122.

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

  As shown in FIG. 4, 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 115a, a doctor blade 116, a first conveying member 112, a second conveying member 113, a partition plate (partition wall) 117, A toner concentration detection sensor 119 is provided.

  The developing tank 111 is a tank for storing a two-component developer containing toner and carrier (hereinafter simply referred to as “developer”). The developing tank 111 is provided with a developing roller 114, a first conveying member 112, a second conveying member 113, and the like. Note that the carrier of this embodiment is a magnetic carrier having magnetism.

  The developing roller 114 is a magnet roller that is rotationally driven around a shaft center by a driving unit (not shown). The developer in the developing tank 111 is pumped and carried on the surface, and toner contained in the developer carried on the surface is photosensitive. This is supplied to the body drum 3.

  The developer conveyed by the developing roller 114 comes into contact with the photosensitive drum 3 at the closest portion. This contact area is the development nip N, and a development bias voltage is applied to the development roller 114 from a power source (not shown) connected to the development roller 114, and the developer on the surface of the development roller 114 is exposed to light. Toner is supplied to the electrostatic latent image on the surface of the body drum 3.

  A doctor blade (layer thickness regulating blade) 116 is disposed at a position close to the surface of the developing roller 114.

  The doctor blade 116 is a plate-like member that extends parallel to the axial direction of the developing roller 114. One end in the short direction is supported by the developing tank 111 and the other end is the developing roller below the developing roller 114 in the vertical direction. 114 is provided to be separated from the surface with a gap. As the material of the doctor blade 116, stainless steel can be used, but aluminum or synthetic resin can also be used.

  The toner concentration detection sensor 119 is mounted on the bottom surface of the developing tank 111 below the second conveying member 113 in the vertical direction, and is provided so that the sensor surface is exposed inside the developing tank 111. The toner concentration detection sensor 119 is electrically connected to a toner concentration control means (not shown). As shown in FIG. 3, the toner concentration control means rotates the toner discharge member 122 in accordance with the toner concentration measurement value detected by the toner concentration detection sensor 119, and enters the developing tank 111 through the toner discharge port 123. Control to supply toner.

  If it is determined that the toner density measurement value by the toner density detection sensor 119 is lower than the toner density setting value, a control signal is sent to the driving means for driving the toner discharge member 122 to rotate, and the toner discharge member 122 is driven to rotate. As the toner concentration detection sensor 119, a general toner concentration detection sensor can be used, and examples thereof include a transmitted light detection sensor, a reflected light detection sensor, and a magnetic permeability detection sensor. Among these, a magnetic permeability detection sensor is preferable.

  A power supply (not shown) is connected to the magnetic permeability detection sensor. The power supply applies a drive voltage for driving the magnetic permeability detection sensor and a control voltage for outputting the detection result of the toner density to the control means. Application of a voltage to the magnetic permeability detection sensor by the power source is controlled by the control means. The permeability detection sensor is a type of sensor that receives the control voltage and outputs the toner density detection result as an output voltage value. Basically, the sensitivity near the median value of the output voltage is good. It is used by applying a control voltage to obtain a voltage. Such type of magnetic permeability detection sensors are commercially available, and examples thereof include TS-L, TS-A, TS-K (all are trade names, manufactured by TDK Corporation) and the like.

  Further, as shown in FIG. 4, a removable developer tank cover 115 is provided on the upper side of the developer tank 111. Further, the developing tank cover 115 is provided with a toner supply port 115 a for supplying unused toner into the developing tank 111.

  As shown in FIG. 1, the toner stored in the toner replenishing device 22 is transferred into the developing tank 111 via the toner transfer mechanism 102 and the toner replenishing port 115a, whereby the toner is supplied to the developing tank 111. It has come to be.

  As shown in FIG. 5, the first transport member 112 includes a screw auger including a spiral first transport blade 112a and a first rotating shaft 112b, and a gear 112c. As shown in FIG. 5, the second transport member 113 includes a screw auger including a spiral second transport blade 113a and a second rotating shaft 113b, and a gear 112c. The first transport member 112 and the second transport member 113 are rotated and driven by a driving means (not shown) such as a motor to stir and transport the developer.

  In the developing tank 111, a partition plate 117 is disposed between the first transport member 112 and the second transport member 113. The partition plate 117 extends in parallel with each axial direction (each rotational axis direction) of the first transport member 112 and the second transport member 113. The interior of the developing tank 111 is partitioned by a partition plate 117 into a first transport path P in which the first transport member 112 is disposed and a second transport path Q in which the second transport member 113 is disposed.

  The partition plate 117 is disposed away from the inner wall surface of the developing tank 111 at both axial ends of the first transport member 112 and the second transport member 113. Thereby, 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 112 and the second transport member 113. ing. In the following, as shown in FIG. 5, 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.

  The first transport member 112 and the second transport member 113 are arranged in parallel so that their peripheral surfaces face each other via the partition plate 117 and their axes are parallel to each other, and rotate in opposite directions. Is set to Then, as shown in FIG. 5, the first transport member 112 transports the two-component developer in the arrow X direction, and the second transport member 113 transports the developer in the arrow Y direction opposite to the arrow X direction. It is set to be.

  The toner replenishing port 115a is a region in the first conveyance path P and is formed at a position on the arrow X direction side from 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 112 and the second transport member 113 are rotationally driven by a driving means (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 arrow X while being stirred by the first transport member 112 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 arrow Y while being stirred by the second transport member 113 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 112 and the second transport member 113 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 make up for the consumed toner, unused toner is replenished to the first transport path P from the toner replenishing port 115a. The replenished toner is mixed and agitated with the developer existing in the first conveyance path P.

Next, characteristic structures of the developing tank 111 and the first transport member 112, which are characteristic points of the present invention, will be described in detail with reference to the drawings.
6 is a cross-sectional view taken along the line BB in FIG. 4, FIG. 7 is a cross-sectional view taken along the line CC in FIG. 4, FIG. 8 is a cross-sectional view taken along the line DD in FIG. It is F section arrow directional view.
4 is a cross-sectional view taken along the line EE of FIG.

As shown in FIG. 6, the developing tank 111 is provided with a first transport path P inclined upward toward the downstream side in the developer transport direction.
As shown in FIG. 9, the bottom surface of the developing tank 111 is the bottom surface P <b> 2 of the downstream end of the first transport path P in the developer transport direction and the end of the upstream end of the second transport path Q in the developer transport direction. As shown in FIG. 8, the bottom surface Q2 of the downstream end of the second transport path Q in the developer transport direction is upstream of the first transport path P in the developer transport direction. It is higher than the bottom surface P1 of the end.

  The second transport path Q and the developing roller 114 are horizontally provided as shown in FIGS. With this configuration, the developer in the axial direction of the developing roller 114 in the second transport path Q is less likely to be biased, so that the developer supply amount in the axial direction of the developing roller 114 is stabilized.

  Further, as shown in FIG. 6, in the first conveying member 112, the spiral pitch D1 on the upstream side in the developer conveying direction of the first conveying blade 112a is larger (longer) than the helical pitch D2 on the downstream side in the developer conveying direction. It is configured as follows. The spiral pitch indicates the length in the rotation axis direction when the conveying blade 112a makes one round around the first rotation axis 112b.

  In this embodiment, the ratio of the spiral pitch D1 and the spiral pitch D2 is set in consideration of the fluidity of the developer, but in this embodiment, the spiral pitch D1 is 1.5 times the spiral pitch D2. It is formed to become.

  As the altitude difference between the bottom surface P2 of the downstream end of the first transport path P in the developer transport direction and the bottom surface Q1 of the upstream end of the second transport path Q in the developer transport direction, The outer diameter (diameter) is preferably not less than 0.3 times and not more than 1.1 times. With this configuration, the developer flows smoothly.

  If it is less than 0.3 times, the difference in height between the bottom surface P2 on the downstream side in the developer transport direction of the first transport path P and the bottom surface Q1 on the upstream side in the developer transport direction of the second transport path becomes small, and sufficient developer transport is achieved. Sex cannot be obtained. On the other hand, if it exceeds 1.1 times, the developer flows to the second transport path Q before reaching the end of the first transport path P, so the distance that the developer can be mixed and agitated becomes short. It becomes an efficient conveyance member design.

  Further, the difference in altitude between the bottom surface Q2 of the downstream end of the second transport path Q in the developer transport direction and the bottom surface P1 of the upstream end of the first transport path P in the developer transport direction is the first transport member. The outer diameter (diameter) of 112 is preferably not less than 0.3 times and not more than 0.8 times. With this configuration, the developer flows smoothly.

  If it is less than 0.3 times, the difference in height between the bottom surface Q2 on the downstream side in the developer transport direction of the second transport path Q and the bottom surface P1 on the upstream side in the developer transport direction of the first transport path P becomes small, and there is sufficient developer. Transportability cannot be obtained. On the other hand, if the ratio exceeds 0.8, the developer flows to the first transport path P before reaching the end of the second transport path Q, so the amount of developer supplied to the developing roller 114 decreases. The image density tends to decrease at the end.

Next, the effect | action in the developer conveyance by the image development apparatus 2 of this embodiment is demonstrated with reference to drawings.
FIG. 10 is an explanatory diagram illustrating a developer conveyance state by rotation of the first conveyance member constituting the developing device according to the present embodiment, and FIG. 11 is conveyed downstream in the developer conveyance direction of the second conveyance path of the development device. FIG. 12 is a diagram illustrating a state in which the developer that has been moved moves to the upstream side in the developer conveyance direction of the first conveyance path, and FIG. 12 illustrates development that has been conveyed to the downstream side in the developer conveyance direction of the first conveyance path of the developing device. FIG. 10 is an explanatory diagram illustrating a state in which the agent moves to the upstream side in the developer conveyance direction of a second conveyance path.

  As shown in FIG. 10, the developer transported by the first transporting member 112 in the developing device 2 has a spiral pitch D1 on the upstream side 112aa of the first transporting member 112 in the developer transporting direction 112a which is on the downstream side 112ab in the developer transporting direction. Since it is formed longer than the helical pitch D2, the developer transport speed is faster on the upstream side than on the downstream side.

  Thus, in the first transport path P, the upstream side of the developer transport direction has a larger transport amount of the developer G than the downstream side in the developer transport direction. Can be avoided. Furthermore, this action lowers the surface (agent surface) of the developer G under the toner replenishing port 115a, so that the replenished toner is easily mixed with the developer G.

  Further, in the developing device 2, the developer G transported downstream of the second transport path Q in the developer transport direction by the second transport member 113 is the developer in the second transport path Q as shown in FIG. Since the bottom surface Q2 of the end on the downstream side in the transport direction is higher than the bottom surface P1 of the end on the upstream side in the developer transport direction of the first transport path P, the bottom surface Q2 of the second transport path Q extends from the first transport path. Move to the bottom face P1 of P.

  Then, the developer G transported from the upstream side in the developer transport direction of the first transport path P to the downstream side by the first transport member 112 is, as shown in FIG. 12, the developer transport direction of the first transport path P. Since the bottom surface P2 of the downstream end portion is higher than the bottom surface Q1 of the upstream end portion of the second transport path Q in the developer transport direction, the bottom surface P2 of the first transport path P extends from the bottom transport surface Q2. Move to bottom Q1.

  In this way, by utilizing the difference in height between the first transport path P and the second transport path Q, the developer G can be transported smoothly without applying excessive stress.

  As described above, according to the present embodiment, in the developing device 2 of the image forming apparatus 100, the first transport path P and the first transport member 112 in the developing tank 111 are directed downstream in the developer transport direction. The bottom surface P2 of the downstream end of the first transport path P in the developer transport direction is configured to be higher than the bottom surface Q1 of the upstream end of the second transport path Q in the developer transport direction. In addition, the bottom surface Q2 of the end of the second transport path Q on the downstream side in the developer transport direction is configured to be higher than the bottom surface P1 of the end of the first transport path P on the upstream side in the developer transport direction. By using the difference in height between the first transport path P and the second transport path Q, the developer G can be transported smoothly without applying excessive stress. As a result, the developer G is clogged or compressed on the downstream side of the first transport path P in the developer transport direction and the downstream side of the second transport path Q in the developer transport direction. It is possible to reduce the amount of the developer G and improve the transportability of the developer G.

  According to the present exemplary embodiment, since the toner can be stably supplied by the developing device 2, the image forming apparatus 100 can obtain a good image without fogging and image density reduction.

  Further, according to the present embodiment, the first transport blade 112a of the first transport member 112 has a helical pitch D1 on the upstream side 112aa in the developer transport direction 112aa larger (longer) than the spiral pitch D2 on the downstream side 112ab in the developer transport direction. Therefore, in the first transport path P, the developer transport speed is higher on the upstream side than the downstream side in the developer transport direction, so that the upstream side is more upstream than the downstream side in the developer transport direction. However, since the amount of developer G transported increases, it is possible to prevent developer G from being biased to a lower position upstream of the developer transport direction due to gravity, and to improve the transportability of developer G.

  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, the developing tank includes a first transport path and a second transport path. The image forming apparatus using the developing device in which the developer is stirred and conveyed by the first conveying member and the second conveying member is not limited to the image forming apparatus and the copying machine having the above-described configuration. Further, it can be developed on 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 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)
22 Toner supply device 100 Image forming device 111 Developer tank (developer container)
112 First conveying member (developer conveying member)
112a 1st conveyance blade 113 2nd conveyance member (developer conveyance member)
113a Second conveying blade 114 Developing roller (developer carrying member)
115a Toner supply port D1 Spiral pitch (upstream side in developer transport direction)
D2 Spiral pitch (downstream of developer transport direction)
P First transport path (developer transport path)
P1 Bottom (upstream side in developer transport direction)
P2 Bottom (downstream side in developer transport direction)
Q Second transport path (developer transport path)
Q1 Bottom (upstream side in developer transport direction)
Q2 Bottom (downstream side in developer transport direction)

Claims (7)

A developer container that contains a developer containing toner and a magnetic carrier; a first conveyance path and a second conveyance path that are partitioned by a partition wall in the developer container and communicated at both ends of the partition wall; A first conveyance member and a second conveyance which are provided in the first conveyance path and the second conveyance path and circulate and convey the developer in the first conveyance path and the second conveyance path in opposite directions to each other. A member, a developer carrying member that carries the developer in the second conveyance path and supplies toner contained in the developer to the photosensitive drum, and a toner for introducing replenishment toner into the first conveyance path In a developing device having a supply port,
In the first transport path and the second transport path, the bottom surface of the end portion on the downstream side in the developer transport direction of the first transport path is higher than the bottom surface of the end portion on the upstream side in the developer transport direction of the second transport path. Configured to be
The developing device, wherein the first conveyance path and the first conveyance member are provided so as to be inclined such that a downstream side in a developer conveyance direction is higher than an upstream side. The second transport path and the developer carrying member are provided substantially horizontally,
The developing device according to claim 1, wherein only the first conveyance path is provided to be inclined.   In the first transport path and the second transport path, the bottom surface of the downstream end of the second transport path in the developer transport direction is more than the bottom surface of the upstream end of the first transport path in the developer transport direction. The developing device according to claim 2, wherein the developing device is configured to be high. The first transport member and the second transport member comprise a screw auger provided with a rotating shaft and a spiral blade body formed to project in a direction perpendicular to the axial direction of the rotating shaft,
4. The pitch of the blade body is configured such that the pitch on the upstream side in the developer transport direction is longer than the pitch on the downstream side in the developer transport direction. 5. Development device.   The height difference between the bottom surface of the downstream end portion of the first transport path in the developer transport direction and the bottom surface of the upstream end portion of the second transport path in the developer transport direction is the outer diameter of the second transport member. 5. The developing device according to claim 1, wherein the developing device is 0.3 times or more and 1.1 times or less.   The height difference between the bottom surface of the downstream end of the second transport path in the developer transport direction and the bottom surface of the upstream end of the first transport path in the developer transport direction is the outer diameter of the first transport member. The developing device according to claim 3, wherein the developing device is 0.3 times or more and 1.1 times or less. 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 the image to form a toner image, a transfer device that transfers the toner image on the surface of the photosensitive drum to a recording medium, and a fixing device that fixes the transferred toner image to the recording medium. In an image forming apparatus for forming an image using toner by electrophotography,
An image forming apparatus using the developing device according to claim 1 as the developing device.

Images