JP2010210780A - Developing device and image forming apparatus - Google Patents

Abstract

An object of the present invention is to provide a developing device capable of preventing the developer from aggregating and adhering to a conveying member.
A developer tank containing a developer containing toner and a magnetic carrier; a transport path provided in the developer tank for transporting the developer; a toner supply port for introducing toner into the transport path; A transport member provided in the transport path and transporting the toner supplied to the transport path and the developer in the transport path while stirring, and a developer provided near the transport path and in contact with the transport member. A developer crushing member that crushes the developer and a developing roller that supplies the conveyed developer to the surface of the photosensitive drum.
[Selection] Figure 2

Description

  The present invention relates to a developing apparatus and an image forming apparatus that perform image formation with a two-component developer containing toner and a magnetic carrier.

2. Description of the Related Art Conventionally, electrophotographic image forming apparatuses are often used as image forming apparatuses such as copying machines and printers.
An electrophotographic image forming apparatus forms an electrostatic latent image on the surface of a photoreceptor (also referred to as a toner image carrier), develops the electrostatic latent image with toner supplied from a developing device, and develops the electrostatic latent image. The toner image is transferred and fixed on a sheet such as paper.

In recent years, two-component developers that are excellent in toner charge stability have been used as developers for the purpose of achieving color and high image quality. The two-component developer is composed of toner and a carrier, and the toner and the carrier are rubbed by stirring them in the developing device, and a properly charged toner is obtained by the friction.
In addition, there is a demand for speeding up and downsizing of the image forming apparatus, and it is necessary to quickly and sufficiently charge the two-component developer and to carry the two-component developer quickly.

  Therefore, in the image forming apparatus, in order to immediately distribute the replenished toner in the two-component developer and to give an appropriate charge amount, two developers that form a path through which the two-component developer is circulated and conveyed A circulation-type developing device has been proposed that includes a conveyance path and two developer stirring members that convey the two-component developer while stirring in the two-component developer conveyance path (see Patent Document 1).

JP-A-2005-24592

  Generally, a conveying member (auger screw) having a spiral blade is used as a conveying member that circulates and conveys the two-component developer in the developing tank while stirring. However, when the rotation speed of the conveying member is increased in order to increase the conveying speed of the two-component developer, the two-component developer is aggregated on the spiral blade due to heat generation and pressure due to friction between the two-component developer and the spiral blade. There was a problem that it was easy to adhere.

  The present invention has been made in view of such circumstances, and by providing a developer crushing member, the developer can be prevented from aggregating and adhering to the conveying member, and has excellent circulation and conveying properties. An object of the present invention is to provide an image forming apparatus including the above.

The present invention provides a developer tank that contains a developer containing toner and a magnetic carrier, a transport path that is provided in the developer tank and transports the developer, a toner supply port that introduces toner into the transport path, A transport member provided in the transport path and transporting the toner supplied to the transport path and the developer in the transport path while stirring, and a developer provided near the transport path and in contact with the transport member. The developing device is provided with a developer crushing member that crushes the developer and a developing roller that supplies the conveyed developer to the surface of the photosensitive drum.
According to this, since the developer crushing member that crushes the developer in contact with the conveyance member that conveys the developer is provided, it is possible to prevent the developer from aggregating and attaching to the conveyance member.
Here, crushing the developer means reducing the soft agglomerated developer and removing the developer fixed to the conveying member. The developer crushing member corresponds to a developer crushing brush described later.

The present invention further includes a partition plate in the developing tank that divides the transport path into a first transport path and a second transport path, and the first transport path and the second transport path are outside both ends of the partition plate. The toner supply port is connected to the upstream side of the first transport path, the developing roller is provided in the vicinity of the second transport path, and the transport member is disposed in the first transport path. The first conveying member and the second conveying member disposed in the second conveying path, wherein the developer crushing member is an upper part in the vertical direction of the partition plate, and the first and second conveying members. A developing device, wherein the developer is stirred and circulated and conveyed in one direction by rotating the first conveying member and the second conveying member in opposite directions to each other. It is to provide.
According to this, when the first and second conveying members rotate, the developer adhering to the first and second conveying members is unwound by the developer crushing member in contact with the first and second conveying members. Since it crushes, it can prevent that a developing agent adheres to the 1st and 2nd conveyance member.

  Here, “communication” means that two conveyance paths are continuous. In addition, communicating with both ends outside the partition plate means that the two conveyance paths divided by the partition plate are continuous outside the both ends of the partition plate, and outside the two ends of the partition plate. This means that there is a communication area where each of the two conveyance paths is connected. That is, the developer that has been transported along the first transport path is transported to the second transport path via one communication region. Further, the developer conveyed on the second conveyance path is conveyed to the first conveyance path via the other communication area.

In the developing device according to the present invention, the developer crushing member includes a plurality of elastic fibers, and a tip end portion of the elastic fibers is in contact with the first conveying member and the second conveying member.
According to this, since the elastic fiber is flexibly deformed according to the shapes of the rotating first and second transport members, when the developer that can adhere to the first and second transport members is crushed, Unevenness of rubbing can be prevented.

In the developing device of the present invention, the developer crushing member includes a developer crushing member rotating shaft and a plurality of elastic fibers provided radially from the developer crushing member rotating shaft, By rotating around the developer crushing member rotation shaft, the tip end portion of the elastic fiber comes into contact with the first conveying member and the second conveying member.
According to this invention, by rotating the developer crushing member, the wear of the elastic fibers contacting the first transport member or the second transport member is made uniform, and only some of the elastic fibers are locally worn. Further, even when it is not during image formation, by rotating the developer crushing member, it is possible to prevent the developer from adhering to the conveying member, and further to remove the developer adhering to the conveying member. .

In the developing device of the present invention, the tip of the elastic fiber may be in contact with the partition plate.
Since the partition plate that divides the transport path in the developing tank into two is surrounded by the first and second transport paths that communicate with each other on the both sides, the frictional heat between the developer and the partition plate tends to be trapped. As a result, when the developer starts to adhere to the partition plate in a coherent state, the developer aggregates over the entire inner wall of the developing tank in contact with the developer, and there is a problem in that the developer's circulating transportability is reduced. .
However, as in the present invention, the elastic fiber functions as a partition plate that separates the first and second transport paths by the tip portion of the elastic fiber coming into contact with the partition plate, and the elastic fiber functions as a partition plate. Since the fiber itself is flexible, the pressure generated by the rotation of the first and second conveying members can be relieved, and the generation of frictional heat can be suppressed.
Furthermore, since the frictional heat accumulation is further suppressed by rotating the developer crushing member, it is possible to prevent the developer from aggregating and adhering to the entire inner wall of the developing tank.

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, and an exposure device that forms an electrostatic latent image on the surface of the photosensitive drum. A toner replenishing device for replenishing toner to the developing device, and a transfer device for transferring a toner image formed on the surface of the photosensitive drum by the developing device to the recording medium using the toner replenished from the toner replenishing device. The present invention also provides an image forming apparatus comprising a fixing device for fixing a toner image on the recording medium.
According to the present invention, the developer is prevented from aggregating and adhering to the inside of the developing device, and the developer transportability is stabilized, so that a constant concentration of toner is supplied to the photosensitive drum, which is stable over a long period of time. Image formation is possible with image density.

1 is an explanatory diagram showing a configuration of an embodiment of an image forming apparatus including a developing device according to the present invention. It is sectional drawing which shows one Example of a structure of the developing device of this invention. 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. 1 is a cross-sectional view showing a configuration of an embodiment of a toner supply device of the present invention. FIG. 6 is an enlarged C-C ′ arrow side view of the periphery of the toner discharge member shown in FIG. 5.

The best mode for carrying out the present invention will be described below with reference to the drawings. However, this does not limit the present invention.
<Configuration of Image Forming Apparatus of the Invention>
FIG. 1 shows a configuration diagram of an embodiment of an image forming apparatus provided with the developing device of the present invention.
As shown in FIG. 1, an image forming apparatus 100 according to the present invention includes 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 a photosensitive member. An exposure unit (exposure device) 1 that forms an electrostatic latent image on the surface of the photosensitive drum 3; a developing device 2 that supplies toner to the electrostatic latent image on the surface of the photosensitive drum 3 to form a toner image; and a developing device 2 A toner replenishing device 22 for replenishing toner, 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. 12.

  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.
The image forming apparatus 100 shown in FIG. 1 is assumed to handle image data for each of four color components of black (K), cyan (C), magenta (M), and yellow (Y). Here, a black image, a cyan image, a magenta image, and a yellow image are formed separately, and one 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 shown. 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 (2a, 2b, 2c, 2d) visualizes (develops) the electrostatic latent image formed on the photosensitive drum 3 with any of K, C, M, and Y toners. is there. Above the developing device 2, there are a toner transfer mechanism 102 (102a, 102b, 102c, 102d), a toner supply device 22 (22a, 22b, 22c, 22d), and a developing tank 111 (111a, 111b, 111c, 111d). With.

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.

The toner image is transferred from the photosensitive drum 3 to the intermediate transfer belt 7 by the intermediate transfer roller 6 that is 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 includes 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 and a pressure roller 82, and 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. Further, 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.

<Description of sheet conveying operation>
Next, the sheet conveying operation by the sheet conveying path S will be described.
In the image forming apparatus 100 of FIG. 1, sheets of a predetermined size are arranged in advance on the paper feed tray 10 and the manual feed tray 20 that is used when printing a small number of sheets.
Pickup rollers 16 (16a, 16b) disposed in the vicinity of both trays (10, 20) 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.

<Configuration of developing device of the present invention>
Next, the developing device 2 will be described with reference to the drawings.
2 is a cross-sectional view showing a configuration of one embodiment of the developing device 2, 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.
The developing device 2 shown in FIG. 2 has a developing roller 114 disposed in the developing tank 111 so as to face the photosensitive drum 3, and supplies toner to the surface of the photosensitive drum 3 by the developing roller 114. The apparatus develops (develops) the electrostatic latent image formed on the surface of the photosensitive drum 3.

2, 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 developer crushing member 118, and a toner concentration detection sensor 119.
The developing tank 111 is a tank that stores a developer containing toner and a carrier (hereinafter also referred to as a two-component developer). In the developing tank 111, a developing roller 114, a first conveying member 112, a second conveying member 113, and a developer crushing member 118 are arranged at positions as shown in FIG. The carrier contained in the developer used in the present invention is a magnetic carrier having magnetism.

  The developing roller 114 conveys the two-component developer in the developing tank 111 to the photosensitive drum 3, and a magnet roller that is driven to rotate around an axis by a driving unit (not shown) can be used. The developing roller 114 is provided so as to face the photosensitive drum 3 and be separated from the photosensitive drum 3 with a slight gap. The two-component developer conveyed by the developing roller 114 comes into contact with the photosensitive drum 3 at the closest portion of the gap. This contact area is called a development nip portion. In the developing nip portion, a developing bias voltage is applied to the developing roller 114 from a power source (not shown) connected to the developing roller 114, and the two-component developer on the surface of the developing roller 114 is changed to an electrostatic latent image on the surface of the photosensitive drum 3. Toner is supplied.

  The doctor blade 116 is a plate-like member extending parallel to the axial direction of the developing roller 114, and one end in the short direction is supported by the developing tank 111 and the other end is the developing roller 114 below the developing roller 114 in the vertical direction. It is provided so as 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 unit (not shown). The toner concentration control unit controls the toner discharge member 122 to rotate according to the toner concentration measurement value detected by the toner concentration detection sensor 119 and supply the toner into the developing tank 111 through the toner discharge port 123. (See FIG. 5).

  If the toner density control unit determines that the measured toner density value detected by the toner density detection sensor 119 is lower than a predetermined set value, it sends a control signal to a driving means (not shown) to drive the toner discharge member 122 to rotate. As the toner concentration detection sensor 119, a general toner concentration detection sensor can be used. For example, a transmitted light detection sensor, a reflected light detection sensor, a magnetic permeability detection sensor, or the like can be used. However, a permeability detection sensor is preferable from the viewpoint of sensitivity.

  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 FIGS. 2 and 4, a detachable developing tank cover 115 is provided above the developing tank 111. Further, the developing tank cover 115 is formed with a toner supply port 115 a for supplying unused toner to the developing tank 111.
As shown in FIG. 1, the toner stored in the toner replenishing device 22 is transferred to the developing tank 111 via the toner transfer mechanism 102 and the toner supply port 115 so that the toner is supplied to the developing tank 111. It has become.

As shown in FIG. 3, the first conveying member 112 is constituted by an auger screw including a spiral first conveying blade 112a, a first rotating shaft 112b, and a first conveying gear 112c, and rotates in a certain direction. Thus, the two-component developer is stirred and conveyed in a certain direction (X direction in FIG. 3).
The second transport member 113 is configured by an auger screw including a spiral second transport blade 113a, a second rotating shaft 113b, and a second transport gear 113c, and rotates in a direction opposite to that of the first transport member 112. As a result, the two-component developer is stirred and conveyed in a certain direction (Y direction in FIG. 3).

  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 to each axial direction (each rotational axis direction) of the first transport member 112 and the second transport member 113. Further, the height of the partition plate 117 is, for example, the same height as a horizontal line connecting the centers of the first rotating shaft 112b and the second rotating shaft 113b from the viewpoint of ensuring developer circulation and the developer crushing effect. do it.

The developer crushing member 118 includes a developer crushing member rotating shaft 118b and a plurality of elastic fibers 118a provided radially from the developer crushing member rotating shaft 118b. The developer crushing member 118 is provided in the vicinity of the two conveyance paths, and is preferably provided, for example, at the upper part of the partition plate 117 in the vertical direction. Further, it is preferably provided rotatably and driven to rotate by a drive motor (not shown).
Still further, the elastic fiber 118a is disposed so that the tip end portion of the elastic fiber 118a contacts at least the surfaces of the first transport member 112 and the second transport member 113, and further contacts the partition plate 117. During the image forming operation, the conveying members (112, 113) rotate, so that the elastic fiber 118a cleans the first conveying member and the second conveying member.
When the elastic fiber 118a contacts with the partition plate 117, the elastic fiber also functions as a partition plate and suppresses generation of frictional heat.

Here, when the elastic fiber 118a comes into contact with the two conveying members (112, 113), the developer attached to these members is crushed.
The developer can be crushed just by contacting the conveying member without rotating the elastic fiber 118a, but by crushing the elastic fiber, the developer can be further crushed, It is possible to prevent local wear of the elastic fibers in contact with each other. Further, when the image is not formed, for example, when waiting for printing or during printing pause, the elastic fiber 118a is rotated, so that the developer can be crushed more effectively and adhered to the conveying member. Can be prevented.

As the elastic fiber 118a, for example, a material such as a resin fiber such as nylon, acrylic, polyolefin, or polyester having a Young's modulus of 1 to 7 GPa can be used.
The length of the elastic fiber 118a can be 3 to 10 mm, for example, and the thickness can be 0.1 to 0.3 mm, for example.
The elastic fiber 118a has a brush density of, for example, 5 to 25 / cm2, and a contact pressure to the conveying member of, for example, 50 to 200 N / m.
Further, the developer crushing member 118 is a rod-like member disposed in parallel with the partition plate 117 over the entire upper part of the partition plate 117, and further extends to a so-called communication area outside both ends of the partition plate 117. Thus, it is preferable that the elastic fiber 118a is also provided in a portion in contact with the conveying member (112, 113) in the communication region.

As shown in FIG. 3, the inside of the developing tank 111 is divided into a first conveyance path P in which the first conveyance member 112 is arranged and a second conveyance path in which the second conveyance member 113 is arranged by a partition plate 117. It is divided into Q.
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.

  Accordingly, the developing tank 111 has a communication region (communication path) that communicates the first conveyance path P and the second conveyance path Q in the vicinity of both axial ends of the first conveyance member 112 and the second conveyance member 113. ) Is formed. As shown in FIG. 3, 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. Installed. As shown in FIG. 3, the first conveying member 112 conveys the two-component developer in the direction of arrow X, and the second conveying member 113 conveys the two-component developer in the arrow Y direction opposite to the arrow X direction. To be driven.
In addition, from the viewpoint of toner agitation, the toner supply port 115a is a region in the first transport path P and at a position closer to the arrow X direction than the second communication path b, as shown in FIGS. It is preferable to form. 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 the first transport member drive motor and the second transport member drive motor, respectively, and transport the two-component developer.
Specifically, in the first transport path P, the two-component 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 two-component 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 two-component developer is transported in the direction of the arrow Y while being stirred by the second transport member 113 and reaches the second communication path b. The two-component 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 two-component developer in the opposite directions while stirring.

  As described above, in the developing tank 111, the two-component developer passes through the first transport path P, the first communication path a, the second transport path Q, and the second communication path b from the first transport path P to the first communication path. Circulating movement is performed in the order of passage a → second conveyance path Q → second communication passage b. Then, while the two-component developer is being conveyed on the second conveyance path Q, the developer roller 114 is carried on the surface by the rotation of the developing roller 114 and pumped up, and the toner in the two-component developer thus pumped is exposed to light. It moves to the body drum 3 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 supply port 115a. The replenished toner is mixed and agitated with the two-component developer existing in the first conveyance path P.

<Configuration of toner supply device>
FIG. 5 is a cross-sectional view of the configuration of an embodiment of the toner replenishing device 22 shown in FIG. FIG. 6 shows an enlarged CC ′ arrow side view around the toner discharge member shown in FIG.
In FIG. 5, the toner replenishing 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 to the developing tank 111 from the toner discharge port 123 via 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. As shown in FIG. 6, the toner discharge member 122 includes an auger including a toner transport blade 122a and a toner discharge member rotating shaft 122b. A screw and a 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 auger screw is set so that the toner is conveyed from both ends in the axial direction 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.
In FIG. 5, the toner stirring member 125 rotates in the direction of the arrow to stir the toner and pumps it toward the toner discharge member 122. At this time, the toner scooping member 125 b rotates and slides on the inner wall of the toner container 121 due to its flexibility, and supplies the toner to the toner discharge member 122. The toner discharge member 122 guides the supplied toner to the toner discharge port 123 by its rotation.

1 Exposure equipment (exposure unit)
2 Developing Device 3 Photosensitive Drum 4 Cleaner Unit 5 Charging Device 6 Intermediate Transfer Roller 7 Intermediate Transfer Belt 8 Transfer Device (Intermediate Transfer Belt Unit)
9 Intermediate transfer cleaning unit 10 Paper feed tray 11 Transfer roller 12 Fixing device (fixing unit)
DESCRIPTION OF SYMBOLS 14 Registration roller 15 Paper discharge tray 16 Pickup roller 20 Manual feed tray 22 Toner supply device 25 Conveyance roller 71 Intermediate transfer belt drive roller 72 Intermediate transfer belt driven roller 73 Intermediate transfer belt tension mechanism 81 Heat roller 82 Pressure roller 100 Image forming apparatus 102 Toner transfer mechanism 111 Developing tank 112 First transport member 113 Second transport member 115a Toner supply port 116 Doctor blade 117 Partition plate 118 Developer crushing member 118a Elastic fiber 118b Developer crushing member rotating shaft 119 Toner density detection sensor P 1 transport path Q second transport path S sheet transport path

Claims (7)

A developer tank containing a developer containing toner and a magnetic carrier;
A conveying path provided in the developing tank for conveying the developer;
A toner supply port for introducing toner into the conveyance path;
A conveying member that is provided in the conveying path and conveys the toner supplied to the conveying path and the developer in the conveying path while stirring;
A developer crushing member that is provided in the vicinity of the conveyance path and contacts the conveyance member to crush the developer;
A developing roller for supplying the conveyed developer to the surface of the photosensitive drum;
A developing device comprising: A partition plate for dividing the transport path into a first transport path and a second transport path is further provided in the developing tank,
The first transport path and the second transport path communicate with each other outside both ends of the partition plate,
The toner supply port is connected to an upstream side of the first conveyance path;
The developing roller is provided in the vicinity of the second conveyance path,
The transport member includes a first transport member disposed in the first transport path and a second transport member disposed in the second transport path,
The developer crushing member is provided at a position in contact with the first and second conveying members at the upper part in the vertical direction of the partition plate,
When the first transport member and the second transport member rotate in opposite directions,
The developing device according to claim 1, wherein the developer is stirred and circulated and conveyed in one direction. The developer crushing member comprises a plurality of elastic fibers,
The developing device according to claim 2, wherein a tip portion of the elastic fiber is in contact with the first transport member and the second transport member. The developer crushing member comprises a developer crushing member rotating shaft and a plurality of elastic fibers provided radially from the developer crushing member rotating shaft,
3. The elastic fiber rotates around the rotation axis of the developer crushing member, so that a tip portion of the elastic fiber comes into contact with the first transport member and the second transport member. Development device.   The developing device according to claim 3, wherein a tip portion of the elastic fiber is in contact with the partition plate.   An image forming apparatus comprising the developing device according to claim 1. A photosensitive drum having an electrostatic latent image formed on the surface;
A charging device for charging the surface of the photosensitive drum;
An exposure device that forms an electrostatic latent image on the surface of the photosensitive drum;
A toner supply device for supplying toner to the developing device;
A transfer device that transfers a toner image formed on the surface of the photosensitive drum by the developing device using toner supplied from the toner supply device to a recording medium;
The image forming apparatus according to claim 6, further comprising a fixing device that fixes the toner image to the recording medium.

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