JP5315428B2 - Toner conveying apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a toner conveying device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof.

  In a conventional image forming apparatus, a powder developer is mainly used, and an electrostatic latent image formed on an image carrier such as a photosensitive drum is visualized by using the developing apparatus, and the visible image (toner) In general, a process of fixing an image) onto a recording medium and then performing a fixing process. The toner remaining on the surface of the image carrier is removed by a cleaning device, and a new toner image is formed. The residual toner removed by the cleaning device is stored in a waste toner bottle. When the waste toner bottle becomes full after printing a predetermined number of sheets, the user is notified and the waste toner bottle is discarded or replaced.

  As a waste toner collecting path from the cleaning device to the waste toner bottle, a toner transport path having a transport screw in a pipe-shaped transport path is known. In such a toner conveyance path, when the outer peripheral track during rotation of the conveyance screw becomes larger than the inner diameter of the conveyance path due to dimensional tolerance of the outer diameter of the conveyance screw and the inner diameter of the conveyance path, warpage of the conveyance screw, or the like, There is a possibility that an excessive rotational load is generated due to friction and the conveying screw does not rotate. Therefore, the dimensions are usually set so that the outer diameter of the conveying screw is smaller than the inner diameter of the conveying path.

  However, when such a dimension setting is performed, there is a clearance (gap) between the conveying screw and the conveying path, so that if the conveying screw is warped, the conveying screw is swung in the radial direction (eccentric. Rotating, hitting the inner surface of the transport path and hitting sound.

  More specifically, when the conveying screw is warped, when the warping is downward, the bending due to the weight of the conveying screw is added in the same direction as the warping, and the amount of deformation increases. On the other hand, when the warp is upward, the deformation due to the weight of the conveying screw acts in the opposite direction to the warp. For this reason, when the conveying screw rotates from a state in which the warping is upward, since the deformation due to the weight of the conveying screw gradually acts in the direction of increasing the warping from the state where the deformation amount is small and balanced, the conveying screw becomes large. It rotates while deforming so as to wave, and collides with the inner surface of the conveyance path. At this time, the generated striking sound increases as the warp increases, and the clearance (gap) between the conveying screw and the inner surface of the conveying path increases, and increases as the weight of the conveying screw increases.

  Therefore, Patent Document 1 provides a portion in which the outer diameter of the spiral protrusion (spiral wing) of the conveying screw is very close to the inner diameter of the cylindrical conveying path, and a part of the outer diameter of the conveying screw is cylindrically conveyed. A toner conveying device is disclosed that is capable of stably rotating while being in contact with the inside of a path.

JP 2002-132109 A

  However, in the method of Patent Document 1, there is a limit in setting the clearance between the conveying screw and the cylindrical conveying path due to dimensional tolerances and assembly tolerances of parts, and when the warp generated in the conveying screw exceeds the clearance, the inner surface of the conveying path. The impact sound could not be prevented reliably. In addition, the rotational load increases because part of the spiral blade of the conveying screw rubs against the inner surface of the conveying path, and if the rotational load further increases due to the presence of toner in the clearance between the conveying screw and the conveying path, the frictional heat causes The fluidity of the toner is lowered and the conveyance efficiency is deteriorated. When the toner is left as it is for a long time, the toner may be solidified.

  In the above, a problem has been described in the case where the toner conveying path having the conveying screw in the pipe-shaped conveying path is used as the waste toner collecting path from the cleaning device to the waste toner bottle. However, in order to supply toner to the developing device. In the toner replenishment path used when replenishing toner from the toner cartridge to the developing device according to the consumption of toner in the developing device, a toner conveying path having a conveying screw in the conveying pipe is also provided. Similar problems arise when used.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention includes a toner conveying device that can prevent the generation of a striking sound due to a collision between the conveying screw and the inner surface of the conveying path and can maintain stable toner conveying performance over a long period of time. An object is to provide an image forming apparatus.

  In order to achieve the above object, the present invention has a circular cross section in which a conveying screw having a rotating shaft and a conveying blade formed on the outer peripheral surface of the rotating shaft, and the conveying screw is rotatably arranged inside. In the toner conveying device comprising a toner conveying pipe, the conveying screw has a substantially V-shaped inclined surface formed symmetrically with respect to the central axis of the toner conveying pipe below the inner wall surface of the toner conveying pipe. The shaft center of the rotation shaft of the conveying screw supported by the inclined surface coincides with the central axis of the toner conveying pipe.

  According to the present invention, in the toner conveying device having the above-described configuration, an angle of the inclined surface with respect to a horizontal plane is 40 ° or more and 60 ° or less.

  According to the present invention, in the toner conveying device having the above-described configuration, the inclined surface is formed so as to face a range within 1/3 of the total length of the conveying screw at a substantially central portion in the longitudinal direction of the conveying screw. It is characterized by that.

  The present invention also provides an image forming apparatus on which the toner conveying device having the above-described configuration is mounted.

  According to the first configuration of the present invention, since the conveying screw rotates with the inclined surface being supported so that the rotation axis is substantially straight, the conveying screw is caused by the interaction between the warping of the conveying screw and the bending due to its own weight. The deformation of the screw is suppressed. Therefore, it is possible to effectively suppress the generation of a striking sound due to a collision between the conveying screw and the inner surface of the toner conveying pipe. Further, since the rotation load of the conveying screw rotates smoothly without increasing, it is possible to suppress a decrease in toner fluidity and solidification due to frictional heat between the conveying screw and the inner surface of the toner conveying pipe.

  Further, according to the second configuration of the present invention, in the toner conveyance device of the first configuration, the angle of the inclined surface with respect to the horizontal plane is set to 40 ° or more and 60 ° or less, thereby preventing the conveyance screw from moving in the horizontal direction. While maintaining the regulation effect, it is possible to avoid an increase in rotational load due to the conveying screw being fitted between the inclined surfaces.

  Further, according to the third configuration of the present invention, in the toner transport device having the first or second configuration, the overall length of the transport screw at the substantially central portion in the longitudinal direction of the transport screw that is likely to warp the transport screw. By forming the inclined surface so as to oppose a range within 1/3 of the angle, it is possible to obtain an inclined surface having a minimum necessary size capable of obtaining an effect of smoothly rotating the conveying screw.

  Further, according to the fourth configuration of the present invention, the mounting of the toner conveyance device having any one of the first to third configurations generates a striking sound due to a collision between the conveyance screw and the inner surface of the toner conveyance pipe. In addition, the image forming apparatus can be effectively prevented from lowering and solidifying the fluidity of the toner in the toner conveying pipe and excellent in quietness and maintenance.

1 is a schematic cross-sectional view showing an overall configuration of an image forming apparatus 1 including a toner conveying device 30 of the present invention. Side surface sectional drawing which shows the structure of the toner conveying apparatus 30 which concerns on one Embodiment of this invention, and the cleaning apparatus 7 vicinity connected with this. The perspective view which shows the state which cut | disconnected the toner conveyance pipe 31 which comprises the toner conveyance apparatus 30 of this invention in the approximate center part of the longitudinal direction. FIG. 3 is an enlarged perspective view near the cross section of the toner transport pipe 31 in FIG. 3. The front view which looked at the cross section of the toner conveyance pipe 31 from the axial direction of the conveyance screw 35 The top view which shows the state which removed the upper pipe 31a of the toner conveyance pipe 31

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a configuration of an image forming apparatus 1 of the present invention. In an image forming apparatus (for example, a printer) 1, when performing an image forming operation, the photosensitive drum 3 that rotates clockwise in FIG. 1 is uniformly charged by the charging unit 2, and an exposure unit (laser scanning) based on image data. The electrostatic latent image is formed on the photosensitive drum 3 by the laser beam from the unit 4), and a developer (hereinafter referred to as toner) is attached to the electrostatic latent image by the developing unit 5 to form a toner image. .

  The toner is supplied to the developing unit 5 from the toner container 6. The image data is transmitted from a personal computer (not shown) or the like. Further, a static elimination device (not shown) for removing residual charges on the surface of the photosensitive drum 3 is provided on the downstream side of the cleaning device 7 with respect to the rotation direction of the photosensitive drum 3.

  A sheet (transfer paper, OHP, or the like) is conveyed from the sheet feeding cassette 8 via the sheet conveyance path 9 toward the photosensitive drum 3 on which the toner image is formed as described above, and is transferred by the registration roller pair 10. 11 (image transfer unit) is adjusted for feeding timing. Then, the toner image formed on the surface of the photosensitive drum 3 is transferred to the sheet by the transfer roller 11. The sheet onto which the toner image has been transferred is separated from the photosensitive drum 3 and conveyed to a fixing unit 13 having a fixing roller pair 12 to fix the toner image. The sheet that has passed through the fixing unit 13 is conveyed to the upper part of the apparatus by the sheet conveying path 14 and is discharged from the discharge roller pair 15 to the discharge tray 16.

  On the other hand, the toner remaining on the surface of the photosensitive drum 3 is removed by the cleaning device 7. The photosensitive drum 3 is neutralized by a neutralizing device (not shown) and then charged again by the charging unit 2, and thereafter image formation is performed in the same manner.

  The photosensitive drum 3 is formed by laminating a photosensitive layer made of amorphous silicon (a-Si) or an organic photosensitive layer (OPC) on an outer peripheral surface of an aluminum drum, for example, so that the surface is charged by the charging unit 2. It has become. Then, an electrostatic latent image in which charging is attenuated is formed on the surface that has received the laser beam from the exposure unit 4. The charging unit 2 charges the surface of the photosensitive drum 3 by discharging (for example, corona discharge). For example, the charging unit 2 is discharged by applying a high voltage using a thin wire or the like as an electrode. .

  The exposure unit 4 irradiates the photosensitive drum 3 with a light beam (for example, a laser beam) based on the image data, and forms an electrostatic latent image on the surface of the photosensitive drum 3. The developing unit 5 includes a developing roller disposed so as to face the photosensitive drum 3, and a developer contained therein is attached to the electrostatic latent image on the photosensitive drum 3 by the developing roller to form a toner image.

  The cleaning device 7 removes the toner (residual toner) remaining on the surface of the photosensitive drum 3 after the toner image is transferred to the sheet. The detailed configuration of the cleaning device 7 will be described later.

  In the fixing unit 13, a fixing roller pair 12 including a heating roller rotating in a clockwise direction in FIG. 1 and a pressure roller rotating in a counterclockwise direction in FIG. ing. The sheet on which the toner image is transferred by the transfer roller 11 is carried into the fixing unit 13 and passes through the fixing nip portion of the fixing roller pair 12. At this time, the toner image on the sheet is melted and fixed to be a permanent image by being heated and pressurized at a predetermined temperature and pressure.

  FIG. 2 is a cross-sectional view of a principal part showing a configuration in the vicinity of the cleaning device 7 including the toner conveying device 30 of the present invention. The housing 7 a of the cleaning device 7 includes a rubbing roller 21, a cleaning blade 22, and a recovery screw 23 that are in line contact with the longitudinal direction of the photosensitive drum 3 by a spring (not shown).

  The rubbing roller 21 is pressed against the photosensitive drum 3 with a predetermined pressure, and is rotated (forward rotation) in the same direction on the contact surface with the photosensitive drum 3 by a driving means (not shown). It is controlled to be faster than the peripheral speed of the body drum 3 (1.2 times here). Examples of the rubbing roller 21 include a structure in which a foam layer made of EPDM rubber and having an Asuka C hardness of 55 ° is formed as a roller body around a metal shaft. The material of the roller body is not limited to EPDM rubber, but may be a rubber or foamed rubber body of another material, and those having an Asuka C hardness of 10 to 90 ° are preferably used.

  A cleaning blade 22 is fixed in contact with the photosensitive drum 3 on the surface of the photosensitive drum 3 downstream of the contact surface with the rubbing roller 21 in the rotation direction. As the cleaning blade 22, for example, a polyurethane rubber blade having a JIS hardness of 78 ° is used, and is attached at a predetermined angle with respect to the tangential direction of the photosensitive drum 3 at the contact point. The material, hardness, dimensions, the amount of biting into the photosensitive drum 3 and the pressure contact force of the cleaning blade 22 are appropriately set according to the specifications of the photosensitive drum 3.

  The residual toner scraped off from the surface of the photosensitive drum 3 by the rubbing roller 21 or the cleaning blade 22 falls due to gravity and gradually accumulates in the housing 7a. Then, as the recovery screw 23 rotates, the toner in the housing 7a is sequentially conveyed in the longitudinal direction of the housing 7a (direction perpendicular to the paper surface of FIG. 2), and a toner discharge portion provided at one end of the bottom surface of the housing 7a. 25 is discharged to the outside of the cleaning device 7.

  The toner conveying device 30 includes a toner conveying pipe 31 and a conveying screw 33. A toner carry-in port 32 and a toner discharge port 33 are formed at both ends of the toner transport pipe 31. The toner carry-in port 32 is connected to the toner discharge unit 25 of the cleaning device 7, and the toner discharge port 33 is connected to a waste toner bottle 37. Has been. The conveying screw 35 includes a conveying blade (spiral blade) 35a and a rotating shaft 35b penetrating through the center thereof, and is rotatably supported in the toner conveying pipe 31. One end of the rotating shaft 35b extends to the outside of the toner conveying pipe 31, and a drive input gear 39 is attached to the tip of the rotating shaft 35b. The drive input gear 39 is connected to a drive motor (not shown), and the conveying screw 35 is rotationally driven at a predetermined speed. As the conveying screw 35 rotates in the direction of arrow A in the drawing, the toner carried into the toner conveying pipe 31 from the cleaning device 7 via the toner inlet 32 is sequentially conveyed in the toner conveying pipe 31 in the direction of arrow B. The toner is stored in the waste toner bottle 37 through the toner discharge port 33.

  3 is a perspective view showing a state in which the toner transport pipe 31 is cut at a substantially central portion in the longitudinal direction, and FIG. 4 is an enlarged perspective view of the vicinity of the cross section of the toner transport pipe 31 (inside the broken line circle S in FIG. 3). 5 is a front view of the cross section of the toner transport pipe 31 as viewed from the axial direction of the transport screw 35, and FIG. 6 is a plan view showing a state where the upper pipe 31a of the toner transport pipe 31 is removed. The toner conveying pipe 31 is formed in a cylindrical shape by combining an upper pipe 31a and a lower pipe 31b having a semicircular cross section.

  Inclined surfaces 40a and 40b are integrally formed in a substantially V shape at a substantially central portion in the longitudinal direction of the lower pipe 31b. The inclined surfaces 40a and 40b are formed symmetrically with respect to the central axis O of the toner conveying pipe, and the conveying screw 35 has a substantially central portion in the longitudinal direction, and the outer peripheral edge of the conveying blade 35a is defined by the inclined surfaces 40a and 40b. Supported. At this time, the axis center of the rotation shaft 35b of the conveying screw 35 coincides with the central axis O of the toner conveying pipe.

  With this configuration, since the conveying screw 35 rotates with the inclined surfaces 40a and 40b being supported so that the rotation shaft 35b is substantially linear, even if the conveying screw 35 is warped, the conveying screw 35 is rotated. During the rotation, the wavy deformation in the radial direction of the conveying screw 35 due to the interaction between the warp and the deflection due to its own weight is suppressed. Therefore, it is possible to effectively suppress the occurrence of a striking sound due to a collision between the conveying screw 35 and the inner surface of the toner conveying pipe 31.

  Further, since the rotation of the conveying screw 35 smoothly rotates without increasing, the generation of frictional heat due to the rotation of the conveying screw 35 can be suppressed, and the fluidity of the toner in the toner conveying pipe 31 is reduced. And solidification can be effectively suppressed.

  Here, the conveying screw 35 is in contact with the inclined surfaces 40a and 40b at two positions obliquely below the conveying blade 35a, but on the opposite side of the inclined surfaces 40a and 40b (above the conveying blade 35a), the conveying blade A predetermined clearance C is secured between 35a and the inner surface of the toner transport pipe 31 (upper pipe 31a). Since the clearance C is set to such an extent that the dimensional tolerance and assembly tolerance of the toner conveyance pipe 31 and the conveyance screw 35 can be absorbed, the rotational load is caused by the contact between the conveyance blade 35a of the conveyance screw 35 and the inner surface of the toner conveyance pipe 31. Or the conveyance screw 35 is sandwiched between the inclined surfaces 40a and 40b and the inner surface of the toner conveyance pipe 31 and cannot be rotated.

  Further, when the angle θ of the inclined surfaces 40a and 40b with respect to the horizontal plane is reduced, the restriction effect on the movement of the conveying screw 35 in the horizontal direction (left and right direction in FIG. 5) is weakened. May swing in the horizontal direction and may collide with the inner side of the toner transport pipe 31. On the other hand, when the angle θ is increased, the conveying screw 35 is fitted between the inclined surfaces 40a and 40b, and the escape space of the conveying screw 35 is restricted in the upward direction, so that the rotational load increases. Therefore, the angle θ of the inclined surfaces 40a and 40b with respect to the horizontal plane is preferably 40 ° or more and 60 ° or less.

  Here, the inclined surfaces 40 a and 40 b are formed only in the substantially central portion in the longitudinal direction of the toner conveying pipe 31, but the inclined surfaces 40 a and 40 b may be formed over the entire longitudinal direction of the toner conveying pipe 31. However, in most cases, the warp of the conveying screw 35 occurs in the central portion in the longitudinal direction, and even if the inclined surfaces 40a and 40b are formed in the vicinity of both end portions in the longitudinal direction, the effect of supporting the conveying screw 35 cannot be expected so much. . As shown in FIG. 6, the inclined surfaces 40 a and 40 b are formed so as to face a range within 1/3 (L / 3) of the total length L of the conveying screw 35 at the substantially central portion in the longitudinal direction of the conveying screw 35. If it does, sufficient effect can be expected.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above-described embodiment, the cleaning device 7 including the rubbing roller 21 and the cleaning blade 22 has been described. However, the toner conveying device 30 of the present invention includes, for example, the cleaning device 7 including only the cleaning blade 22 and the cleaning blade. It can replace with 22 and can apply to the cleaning apparatus of various structures, such as the cleaning apparatus 7 provided with the fur brush.

  In the above embodiment, the inclined surfaces 40a and 40b are integrally formed with the lower pipe 31b. However, the inclined surfaces 40a and 40b may be fixed to the lower pipe 31b as separate members. Further, the inclined surfaces 40a and 40b may be slightly concave or convex instead of flat surfaces. Moreover, in the said embodiment, although the conveyance screw 35 by which the helical conveyance blade | wing 35a was continuously provided around the rotating shaft 35b is used, the conveyance blade 35a is not limited to a helical shape, For example, several half moons A plate-like plate (a plate obtained by dividing a circular plate into two parts) may be alternately arranged around the rotation shaft 35b at a predetermined inclination angle to form a conveyance blade 35a.

  In the above embodiment, the example in which the toner conveying device 30 of the present invention is disposed in the waste toner conveying path from the cleaning device 7 to the waste toner bottle 37 has been described. For example, the toner conveying path from the toner container 6 to the developing unit 5 is described. The same applies to the above.

  The present invention can be used for a toner conveying device having a toner conveying pipe and a conveying screw disposed in the toner conveying pipe. By using the present invention, it is possible to suppress the generation of impact sound due to the collision between the conveying screw and the inner surface of the toner conveying pipe, and to effectively prevent the decrease in the fluidity and solidification of the toner due to the increase in the rotational load of the conveying screw. Can do.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Photosensitive drum 7 Cleaning apparatus 21 Rub roller 22 Cleaning blade 30 Toner conveyance apparatus 31 Toner conveyance pipe 31a Upper pipe 31b Lower pipe 32 Toner carry-in port 33 Toner discharge port 35 Conveyance screw 35a Conveyance blade 35b Rotating shaft 37 Waste toner bottle 40a, 40b Inclined surface

Claims (4)

A conveying screw having a rotating shaft and a conveying blade formed on the outer peripheral surface of the rotating shaft;
A toner conveying pipe having a circular cross section in which the conveying screw is rotatably arranged;
A toner conveying device comprising:
The conveying screw is supported by a substantially V-shaped inclined surface formed symmetrically with respect to the central axis of the toner conveying pipe below the inner wall surface of the toner conveying pipe, and is supported by the inclined surface. The toner conveying device according to claim 1, wherein an axis center of a rotating shaft of the conveying screw coincides with a central axis of the toner conveying pipe.   The toner conveying device according to claim 1, wherein an angle of the inclined surface with respect to a horizontal plane is not less than 40 ° and not more than 60 °.   The said inclined surface is formed so that it may oppose the range within 1/3 of the full length of the said conveyance screw in the approximate center part of the longitudinal direction of the said conveyance screw. The toner conveying device according to claim.   An image forming apparatus on which the toner conveying device according to claim 1 is mounted.

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