JP2019008103A - Image forming apparatus and developing device - Google Patents

Abstract

To reduce the amount of developer separated from a developer holding body attaching again to the developer holding body, compared with a technology not including a partition part that partitions an upper part in the gravity direction of a space between a conveying member that conveys developer and another conveying member that is opposed to the conveying member and conveys developer in a direction opposite to that of the above-mentioned conveying member.SOLUTION: An image forming apparatus 10 comprises: a photoreceptor drum 102; a developing roller 210; a first auger 222 that supplies developer to the developing roller 210; a second auger 232 that supplies developer to the first auger 222; a third auger 240 that conveys developer in a direction opposite to the direction in which the second auger 232 conveys developer; and a partition part 260 that partitions an upper part in the gravity direction of a space between the second auger 232 and third auger 240.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus and a developing device.

  In Patent Document 1, a developer carrying body provided to face the electrostatic latent image holding body and a first auger that transports the developer along the axial direction of the developer carrying body. And a second auger that is provided substantially parallel to the first agitating chamber, communicates with the first agitating chamber at both ends, and conveys the developer in a direction opposite to the first auger. A developing device having a second agitating chamber, the second agitating chamber being provided almost immediately below the first agitating chamber, and above the second auger in the second agitating chamber, A developing device is described that includes a third auger that conveys developer in a direction opposite to the second auger.

JP-A-6-51634

  If the developer separated from the developer holder is reattached to the developer holder, the toner concentration in the developer supplied from the developer holder to the image carrier may become unstable, and the image formed The quality of the product may be degraded.

  The present invention is a partition that partitions the upper side in the gravity direction of a space between a transport member that transports a developer and another transport member that faces the transport member and transports the developer in a direction opposite to the transport member. It is an object to reduce the amount of the developer separated from the developer holding body and reattached to the developer holding body, as compared with a technique having no part.

The present invention according to claim 1
An image carrier for holding an image;
A developer holder for holding a developer to be supplied to the image carrier;
A first conveying member that supplies the developer to the developer holder while conveying the developer in the axial direction of the developer holder;
A second conveying member that supplies the developer to the first conveying member while conveying the developer in the axial direction of the developer holder;
A third conveying member that faces the second conveying member and conveys the developer in a direction opposite to the direction in which the second conveying member conveys the developer;
A partition that partitions the upper side in the direction of gravity of the space between the second transport member and the third transport member;
An image forming apparatus having

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the lower end of the partitioning portion is located below the upper end of the second conveying member in the gravity direction.

  A third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein a lower end of the partitioning portion is located above the lower end of the third conveying member in the gravity direction.

  According to a fourth aspect of the present invention, in the image according to any one of the first to third aspects, the lower end of the partitioning portion is positioned below the upper end of the developer being transported by the second transport member in the direction of gravity. Forming device.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the second transport member is located below the first transport member in the direction of gravity.

The present invention according to claim 6 provides:
A developer holding body for holding a developer to be supplied to an image holding body for holding an image;
A first conveying member that supplies the developer to the developer holder while conveying the developer in the axial direction of the developer holder;
A second conveying member that supplies the developer to the first conveying member while conveying the developer in the axial direction of the developer holder;
A third conveying member that faces the second conveying member and conveys the developer in a direction opposite to the direction in which the second conveying member conveys the developer;
A partition that partitions the upper side in the direction of gravity of the space between the second transport member and the third transport member;
Is a developing device.

  According to the first aspect of the present invention, the space between the conveying member that conveys the developer and the other conveying member that opposes the conveying member and conveys the developer in the opposite direction to the above-described conveying member. It is possible to provide an image forming apparatus capable of reducing the amount of the developer separated from the developer holding member from reattaching to the developer holding member, as compared with a technique that does not have a partition part that partitions the upper side in the direction of gravity. it can.

  According to the second aspect of the present invention, the developer separated from the developer holding body compared to the apparatus in which the lower end of the partitioning portion is located above the upper end of the second conveying member in the gravitational direction becomes the developer holding body. The amount of reattachment can be reduced.

  According to the third aspect of the present invention, the developer can be smoothly moved in the developing device as compared with the device in which the lower end of the partitioning portion is lower than the lower end of the first conveying member. .

  According to the fourth aspect of the present invention, in the developing device, the lower end of the partition portion is compared with the device in which the second conveying member is located above the upper end of the developer being conveyed in the gravity direction. It is possible to make it difficult for the floating developer to leak out of the developing device.

  According to the fifth aspect of the present invention, the developing device is downsized in the horizontal direction as compared with the device in which the second transport member and the first transport member are arranged so as to overlap in the direction of gravity. be able to.

  According to the sixth aspect of the present invention, the space between the conveying member that conveys the developer and the other conveying member that faces the conveying member and conveys the developer in the opposite direction to the above-described conveying member. Compared to a technique that does not have a partitioning part that partitions the upper side in the direction of gravity, it is possible to provide a developing device that can reduce the amount of developer that is separated from the developer holding body and reattaches to the developer holding body. .

1 is a diagram illustrating a schematic configuration of an image forming apparatus used in an embodiment of the present invention. FIG. 2 is a diagram illustrating a cross section of a first example of a developing device included in the image forming apparatus illustrated in FIG. 1. FIG. 3 is a diagram illustrating movement of a developer in the developing device illustrated in FIG. 2. FIG. 4 is a diagram illustrating a cross section of a second example of a developing device included in the image forming apparatus illustrated in FIG. 1. FIG. 5A is a diagram illustrating a first comparative example of the developing device, FIG. 5B is a diagram illustrating a second comparative example of the developing device, and FIG. 5C is a diagram illustrating development. It is a figure which shows the 3rd comparative example of an apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating an example of an image forming apparatus 10 used in an embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus 10 includes an image forming apparatus main body 12, and an image forming unit 100 that forms an image in the image forming apparatus main body 12, a supply device 300, and a conveyance path 400 are arranged. Has been.

  The image forming unit 100 is an example of an image holding body that holds an image, and is charged by the photosensitive drum 102 that rotates in the direction of arrow a, the charging device 104 that charges the photosensitive drum 102, and the charging device 104. For example, a latent image forming apparatus 106 that forms a latent image by irradiating light onto the surface of the photosensitive drum 102, and the latent image formed by the latent image forming apparatus 106 is developed using a two-component developer to form a toner image. And a developing device 200. Details of the developing device 200 will be described later.

  The image forming unit 100 transfers, for example, a toner image developed by the developing device 200 to a recording medium such as paper, and fixing for fixing the toner image transferred to the recording medium by the transfer device 110 to the recording medium. And a device 130.

  The transfer device 110 is endless, and is rotatably suspended, for example, on three support rolls 114, and includes a transport member 112 that transports a recording medium by rotating in the direction of arrow b, and a transport member 112. A transfer roll 116 to which a transfer bias is applied, which is in contact with the surface opposite to the surface on which the photosensitive drum 102 is in contact.

  The fixing device 130 includes a heating roll 134 having a heat source 132 and a pressure roll 136 that presses the recording medium against the heating roll 134, and fixes the toner image on the recording medium using heat and pressure.

  The image forming unit 100 further includes a cleaning device 108. The cleaning device 108 cleans the surface of the photosensitive drum 102 after the toner image is transferred onto the recording medium by the transfer device 110.

  The supply device 300 is a device that supplies a recording medium to the image forming unit 100. The storage unit 302 stores the stacked recording media, and the recording medium stored in the storage unit 302 faces the image forming unit 100. And a delivery roll 304 for feeding out.

  The conveyance path 400 conveys the recording medium from the supply device 300 to the image forming unit 100, and further conveys the recording medium on which the image is formed by the image forming unit 100 toward the outside of the image forming apparatus main body 12. . Further, in order from the upstream side in the conveyance direction of the recording medium along the conveyance path 400, the above-described delivery roll 304, the conveyance roll 410 that conveys the recording medium, the registration roll 420, the above-described transfer device 110, and the above-mentioned description. The fixing device 130 is disposed.

  The registration roll 420 temporarily stops the movement of the leading end of the recording medium, and resumes the movement of the leading end of the recording medium so as to coincide with the timing at which the image forming unit 100 forms an image.

  As described above, in the image forming apparatus 10, the image forming unit 100 forms a toner image on the recording medium supplied by the supply apparatus 300, and the recording medium on which the toner image is formed is outside the image forming apparatus main body 12. And discharged.

  FIG. 2 shows a first example of the developing device 200. The developing device 200 of the first example is a device that develops a latent image using a developer in which, for example, a nonmagnetic toner that is negatively charged and a magnetic carrier that is positively charged are mixed, for example. As shown in FIG. 2, the developing device main body 202 is provided, and the developing roll 210 is disposed in the developing device main body 202. Here, the developing roll 210 is an example of a developer holding body that holds the developer supplied to the image holding body (photosensitive drum 102).

  The developing roll 210 has, for example, a cylindrical magnet member 212 and a cylindrical sleeve, for example, which covers the magnet member 212 and rotates in the direction of arrow c while being supported by the magnet member 212.

  The magnet member 212 has, for example, five magnetic poles. More specifically, the magnet member 212 includes, for example, an attracting magnetic pole N1, a conveying magnetic pole S1, a conveying magnetic pole N2, a developing magnetic pole S2, and a separating magnetic pole N3.

  The attracting magnetic pole N <b> 1 is used to attract the developer conveyed to the developing roll 210 side by a first auger 222 described later to the surface of the developing sleeve 214.

  The conveying magnetic pole S1 is disposed downstream of the attracting magnetic pole N1 in the rotation direction of the developing sleeve 214, and maintains the adsorption of the developer to the surface of the developing sleeve 214, thereby rotating the developing sleeve 214. Along with this, it is used to transport the developer.

  The transport magnetic pole N2 is disposed downstream of the transport magnetic pole S1 in the rotation direction of the developing sleeve 214, and maintains the adsorption of the developer to the surface of the developing sleeve 214, similarly to the transport magnetic pole S1. Therefore, it is used for transporting the developer as the developing sleeve 214 rotates.

  The developing magnetic pole S2 is disposed on the downstream side of the conveying magnetic pole N2 in the rotation direction of the developing sleeve 214, and is disposed so as to face the moving region where the toner moves from the surface of the developing sleeve 214 to the photosensitive drum 102. In addition, it is used to form developer spikes in the vicinity of the photosensitive drum 102 and develop the latent image formed on the surface of the photosensitive drum 102 with toner.

  The separation magnetic pole N <b> 3 is disposed downstream of the development magnetic pole S <b> 2 in the rotation direction of the development sleeve 214 and is used to separate the developer from the surface of the development sleeve 214.

  A first agitating chamber 220 for conveying the developer and agitating the developer is provided in the developing device main body 202, and the first auger 222 is provided in the first agitating chamber 220. Has been placed.

  The first auger 222 is an example of a first conveying member that supplies developer to the developer holding body while conveying the developer in the axial direction of the developer holding body (developing roll 210). The developer is conveyed so as to be rotated in the direction and pushed out by the spiral blade 224. More specifically, the first auger 222 moves the developer from the back side of the paper surface in FIG. 2 to the front side of the paper surface in FIG. And (to the left in FIG. 2) move the developer.

  In the developing device main body 202, a second stirring chamber 230 for conveying the developer and stirring the developer is further provided, and the second auger 232 is provided in the second stirring chamber 230. Is arranged.

  The second auger 232 supplies the developer to the first conveying member (first auger 222) while conveying the developer in the axial direction of the developer holder (developing roll 210). The developer is conveyed so as to rotate in the direction of arrow e and to be pushed out by the spiral blade 234. More specifically, the second auger 232 conveys the developer from the front side of the paper surface in FIG. 2 to the back side of the paper surface in FIG. 2 in the second stirring chamber 230.

  The first agitation chamber 220 and the second agitation chamber 230 communicate with each other on the front side in FIG. 2, that is, on one end side in the longitudinal direction of the first auger 222 and the second auger 232. More specifically, a through-hole 204 (see FIG. 3) is formed in the developing device main body 202 so that the developer can move from the first stirring chamber 220 to the second stirring chamber 230. Yes. Then, the developer moves from the first stirring chamber 220 to the second stirring chamber 230 so as to fall through the through-hole 204.

  Further, the first stirring chamber 220 and the second stirring chamber 230 communicate with each other on the back side in FIG. 2, that is, on the other end side in the longitudinal direction of the first auger 222 and the second auger 232. Yes. More specifically, a through-hole 206 (see FIG. 3) is formed in the developing device main body 202 so that the developer can move from the second stirring chamber 220 to the first stirring chamber 230. Yes. Then, the second auger 232 moves the developer from the second stirring chamber 230 to the first stirring chamber 220 through the through hole 206 and pushes it up.

  In this way, the developer is moved so as to pass through the through hole 206 from the second stirring chamber 230 to the first stirring chamber 220, so that the developer is moved upward. The developer tends to stay and the height of the developer in the second stirring chamber 230 tends to be high on the through hole 206 side and low on the through hole 204 side. Then, the difference in the height of the developer in the second stirring chamber 230 may cause deterioration in image quality of an image formed by the image forming apparatus 10 such as density unevenness. For this reason, in the image forming apparatus 10, the difference in the height of the developer in the second stirring chamber 230 is reduced by using the third auger 240.

  The third auger 240 faces the second transport member (second auger 232), and is a third transport member that transports the developer in the direction opposite to the direction in which the second transport member transports the developer. As an example, the developer is conveyed so as to rotate in the direction of the arrow f and be pushed out by the spiral blade 242. The direction in which the third auger 240 transports the developer is the direction from the through hole 206 side to the through hole 204 side, which is the opposite direction to the direction in which the second auger 232 transports the developer as described above. It has become.

  As described above, since the third auger 240 conveys the developer from the through hole 206 side to the through hole 204 side, the retention of the developer in the vicinity of the through hole 206 in the second stirring chamber 230 is alleviated. The difference in developer height in the second stirring chamber 230 is alleviated.

  As shown in FIG. 2, the third auger 240 is located between the separation magnetic pole N <b> 3 of the magnet member 212 and the second auger 232. For this reason, the movement of the developer separated from the developing roller 210 in the vicinity of the separation magnetic pole N3 is prevented by the third auger, and the developer separated in the vicinity of the separation magnetic pole N3 does not move toward the second auger 232. There is a risk of staying in the vicinity of the developing roll 210. Then, the developer staying in the vicinity of the developing roll 210 may be reattached to the developing roll 210 without being stirred in the second stirring chamber 230 or the first stirring chamber 220, and the developer is transferred to the developing roll 210. By reattaching, the quality of the image formed by the image forming apparatus 10 may be deteriorated.

  For this reason, in this image forming apparatus 10, a partition portion 260 is provided to suppress the reattachment of the developer separated from the developing roll 210 to the photosensitive drum 102.

  The partition 260 is an example of a partition that partitions the upper side in the direction of gravity of the space between the second transport member (second auger 232) and the third transport member (third auger 240). The upper end side is fixed to the developing device main body 202, and the lower end portion 260 a side is located between the second auger 232 and the third auger 240. The partition portion 260 suppresses the movement of the developer from the second auger 232 side to the third auger 240 side, and from the developing roll 210 by being pushed by the developer moving to the third auger 240 side. Reattachment of the separated developer to the developing roll 210 is suppressed.

  A lower end portion 260 a that is a lower end of the partition portion 260 is located below the upper end portion of the second auger 232 in the gravity direction. For this reason, compared with the case where the lower end part 260a is located above the lower end part of the 2nd auger 232, the quantity of the developer which goes to the 3rd auger 240 side from the 2nd auger 232 side is suppressed. It is possible to make it difficult for the developer separated from the developing roll 210 to adhere to the developing roll 210 again.

  Further, the lower end portion 260 a of the partition portion 260 is located above the lower end of the third auger 240 in the gravity direction. For this reason, compared with the case where the lower end part 260a is located below the lower end of the third auger 240 in the direction of gravity, the movement of the developer in the developing device main body 202 can be made smoother. More specifically, as compared with the case where the lower end portion 260a is positioned below the lower end of the third auger 240 in the direction of gravity, the developer separated from the developing roll 210 in the vicinity of the separation magnetic pole N3. The movement toward the third auger 240 can be made smooth.

  The lower end 260a of the partition 260 is a developer that is being transported by the second auger and is stirred in the second stirring chamber 230, and is lower in the gravity direction than the upper end of the transported developer. Is located. For this reason, the lower end portion 260a of the partitioning portion 260 is a developer that is being conveyed by the second auger, and is located above the upper end of the developer that is conveyed and stirred in the second agitating chamber 230 in the gravity direction. Compared to the positioned technology, the toner scattered in the air near the second auger or the like is less likely to leak out of the developing device main body 202.

  In the first example of the developing device 200, the lower end portion 260a of the partition portion 260 is located on the third auger 240 side (left side in FIG. 2) in the horizontal direction of the partition portion 260.

  In the image forming apparatus 10, the second auger 232 is located below the first auger 222 in the direction of gravity. Therefore, compared to the case where the second auger 232 and the first auger 222 are arranged so as to overlap in the direction of gravity, the developing device 200 can be downsized in the horizontal direction, and the image in the horizontal direction can be reduced. The forming apparatus 10 can be reduced in size.

  FIG. 3 is a schematic diagram for explaining the movement of the developer in the developing device 200. In FIG. 3, the right side corresponds to the back side in FIG. 2, and the left side corresponds to the front side in FIG. 3 indicates the flow of the developer in the developing device main body 202.

  As shown in FIG. 3, the developer separated from the developing roll 210 is conveyed to the right side in FIG. 3 by the second auger 232 in the second stirring chamber 230. Then, the developer conveyed to the right side in FIG. 3 by the first auger 232 moves to the first stirring chamber 220 so as to pass through the through hole 206.

  At this time, the developer tends to stay in the vicinity of the through hole 206, and the height of the developer in the second stirring chamber 230 may be higher on the through hole 206 side and lower on the opposite side to the through hole 206. For this reason, the third auger 240 facing the second auger 232 conveys the developer in the direction opposite to the second auger 232, that is, away from the through hole 206, and develops in the vicinity of the through hole 206. The retention of the agent is suppressed.

  The developer that has passed through the through hole 206 and has reached the first stirring chamber 220 is conveyed to the left side in FIG. 3 by the first auger 222, and a part of the developer reaches the developing roll 210 in the vicinity of the attracting magnetic pole N1. Adsorbed.

  Then, the developer separated from the developing roll 210 is collected into the second stirring chamber 230 and conveyed again to the right side in FIG. 3 by the second auger 232.

  FIG. 4 shows a second example of the developing device 200. In the first example of the developing device 200 described above, the lower end portion 260a of the partition portion 260 is located on the third auger 240 side in the horizontal direction of the partition portion 260 (left side in FIG. 2). On the other hand, in the second example of the developing device 200, the lower end portion 260a of the partition portion 260 is located on the second auger 232 side (right side in FIG. 4) in the horizontal direction of the partition portion 260. Except for the position of the lower end portion 260a, the configuration of the second example of the developing device 200 is the same as the configuration of the second example of the developing device 200 described above.

  FIG. 5A shows a first comparative example of the developing device 200. The developing device 200 according to the first comparative example does not include the partition portion 260 included in the developing device 200 to which the present invention is applied. In the developing device 200 according to the first comparative example, the developer separated from the developing roll 210 in the vicinity of the separation magnetic pole N3 easily adheres to the developing roll 210, and density unevenness is likely to occur in an image formed on the recording medium. .

  FIG. 5B shows a second comparative example of the developing device 200. Although the developing device 200 in the second comparative example includes the partition portion 260, the lower end portion 260 a of the partition portion 260 is located above the upper end of the second auger 232 in the gravity direction. Also in the second comparative example, the developer separated from the developing roll 210 in the vicinity of the separation magnetic pole N3 is likely to be reattached to the developing roll 210, and density unevenness is likely to occur in the image formed on the recording medium.

  FIG. 5C shows a third comparative example of the developing device 200. Although the developing device 200 according to the third comparative example includes the partition portion 260, the lower end portion 260a of the partition portion 260 is located above the upper end of the second auger 232 in the gravity direction, and the lower end portion 260a. Is located above the second comparative example in the direction of gravity. In the second comparative example, the developer separated from the developing roll 210 in the vicinity of the separation magnetic pole N3 is more easily reattached to the developing roll 210 than in the second comparative example, and is further further than in the second comparative example. Density unevenness tends to occur in an image formed on a recording medium.

DESCRIPTION OF SYMBOLS 10: Image forming apparatus 102: Photoconductor drum 200: Developing device 204: Through hole 206: Through hole 210: Developing roll 222: First auger 232: Second auger 240: Third auger 260: Partition 260a: Lower end N3: Separating magnetic pole

Claims (6)

An image carrier for holding an image;
A developer holder for holding a developer to be supplied to the image carrier;
A first conveying member that supplies the developer to the developer holder while conveying the developer in the axial direction of the developer holder;
A second conveying member that supplies the developer to the first conveying member while conveying the developer in the axial direction of the developer holder;
A third conveying member that faces the second conveying member and conveys the developer in a direction opposite to the direction in which the second conveying member conveys the developer;
A partition that partitions the upper side in the direction of gravity of the space between the second transport member and the third transport member;
An image forming apparatus.   The image forming apparatus according to claim 1, wherein a lower end of the partitioning portion is positioned below the upper end of the second transport member in the gravity direction.   3. The image forming apparatus according to claim 1, wherein a lower end of the partitioning portion is positioned above the lower end of the third transport member in a gravitational direction.   4. The image forming apparatus according to claim 1, wherein a lower end of the partitioning portion is located below the upper end of the developer being transported by the second transport member in the direction of gravity.   5. The image forming apparatus according to claim 1, wherein the second transport member is positioned below the first transport member in the direction of gravity. A developer holding body for holding a developer to be supplied to an image holding body for holding an image;
A first conveying member that supplies the developer to the developer holder while conveying the developer in the axial direction of the developer holder;
A second conveying member that supplies the developer to the first conveying member while conveying the developer in the axial direction of the developer holder;
A third conveying member that faces the second conveying member and conveys the developer in a direction opposite to the direction in which the second conveying member conveys the developer;
A partition that partitions the upper side in the direction of gravity of the space between the second transport member and the third transport member;
A developing device.

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