JP2008046233A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To leak developer from a weak sealing property such as a joint of a conveyance path when a developer container is disposed in the vicinity of a developing device, or to convey developer by pressure. There was a problem.
By forming a part of the wall surface of the second developer accommodating portion with a deformable elastic body, when the toner is transported from the hopper by the transport screw, the elastic body is deformed to the outside and the second developer accommodating section is deformed to the second side. Fluctuation in atmospheric pressure in the developer container is reduced, toner does not ooze out or eject from the joint, and the main body of the apparatus is not contaminated by toner scattering. Also, toner conveyance efficiency is reduced due to fluctuations in atmospheric pressure. An image forming apparatus is provided.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a printer that visualizes an electrostatic latent image on a photosensitive drum or a photosensitive belt as an image carrier using a developer (hereinafter referred to as toner).

An image forming apparatus such as an electrophotographic copying machine or a printer has a developer dispenser for supplying developer to a developing device. The developer dispenser is composed of a developer bottle containing a developer and a device for delivering the developer from the developer bottle. A developer dispenser is disposed above the image forming apparatus main body so that the developer bottle can be easily replaced, and the developer is replenished to the developing device via a replenishment conveyance path disposed obliquely. Yes (see, for example, Patent Document 1 and Patent Document 2).
Japanese Patent Laid-Open No. 2000-242072 JP 2005-284179 A

  In the above-described image forming apparatus, since the developer transport path between the developer dispenser and the developer is very long, the developer replenishment accuracy becomes unstable, and the toner density in the developer varies. In some cases, the image quality is degraded. Therefore, in order to stabilize the replenishment accuracy, a developer container for temporarily storing the developer that has been transported is provided in the vicinity of the developing device in the middle of the developer replenishment path, and the developer that has been stored once is developed. There is a configuration to replenish the vessel as appropriate. However, if a large developer accommodating portion is provided in the vicinity of the developing device, the size of the image forming apparatus is increased, so that the developer accommodating portion has a small volume. The developer accommodating portion is provided with a replenishment screw for appropriately supplying the developer to the downstream side, and is closed because the developer is filled in the replenishment screw portion. In this state, when the developer is replenished from the upstream, that is, from the developer dispenser, the pressure inside the small volume developer container becomes higher than the atmospheric pressure, and the developer conveyance path joints, etc. The developer leaks from a place having a poor sealing property, or the developer transport is hindered by the pressure, and the developer transport efficiency is lowered.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of preventing a developer from leaking out during transport of a developer or replenishing a developer and capable of stably supplying the developer.

  The developer transported in the middle of the developer transport path between the developing device that develops the latent image on the photosensitive member and the first developer storage portion that stores the developer to be supplied to the developing device is temporarily stored. In the image forming apparatus provided with the second developer containing portion having a supply means for supplying the developer according to the developer consumption of the developing device, a part of the container wall surface of the second developer containing portion is deformed It consists of a possible elastic body part.

  According to the present invention, since a part of the wall surface of the sub hopper portion is configured by a deformable elastic body, when the toner is transported from the hopper by the transport screw, the elastic body is deformed to the outside and the atmospheric pressure in the sub hopper varies. Is reduced, toner does not ooze out or eject from the joint, and the main body of the apparatus is not soiled by scattered toner. Further, there is no decrease in toner conveyance efficiency due to fluctuations in atmospheric pressure.

  Further, according to the present invention, since a communication pipe different from the toner conveyance path is provided between the hopper and the sub hopper, air moves through the communication pipe and the atmospheric pressure in the sub hopper does not fluctuate. When the toner is conveyed from the hopper by the conveying screw, the fluctuation of the atmospheric pressure in the sub hopper is reduced, the toner does not ooze out or eject from the joint portion, and the apparatus main body is not contaminated by the scattering of the toner. Further, there is no decrease in toner conveyance efficiency due to fluctuations in atmospheric pressure.

  Furthermore, according to the present invention, the air permeable filter is disposed on a part of the wall surface of the sub hopper, so that when the toner is transported from the hopper by the transport screw, the air escapes from the filter to the outside and the sub hopper. Fluctuations in the internal pressure are reduced, toner does not ooze out or eject from the joint, and the apparatus main body is not soiled by toner scattering. Further, there is no decrease in toner conveyance efficiency due to fluctuations in atmospheric pressure.

(Example 1)
FIG. 2 is a main sectional view of a printer as an image forming apparatus to which the present invention is applicable.

  In FIG. 2, an image forming unit 2 is formed in the upper part of the printer main body 1 and a sheet conveying unit 4 is formed in the lower part. The image forming unit 2 forms an electrostatic latent image on the photosensitive drum 20 as an image carrier, a charger 21 that uniformly charges the surface of the photosensitive drum, and a photosensitive drum on the Y, M, C, and Bk stations. Laser scanner unit 22, developing unit 23 that develops the electrostatic latent image on the photosensitive drum into a toner image having a particle diameter of 5 to 10 μm, and primary transfer that transfers the toner image on the photosensitive drum to the intermediate transfer belt 24. A roller 25 and a cleaner 26 for removing residual toner on the photosensitive drum are provided. The intermediate transfer belt 24 is stretched around a drive roller 27, a secondary transfer inner roller 28, and a tension roller 29.

  Next, the configuration of the paper transport unit 4 will be described. The recording paper P stored in the paper cassette 40 is separated one by one by a paper feed roller 41 and a separation roller pair 42 and conveyed to a registration roller pair 44 by a plurality of conveyance rollers 43. The recording paper that has reached the registration roller pair is conveyed in time with the position and timing of the toner image on the intermediate transfer belt 24.

  The toner image on the intermediate transfer belt 24 is transferred onto the recording paper P by the secondary transfer outer roller 45. Downstream of the secondary transfer outer roller, a conveyance belt 46 that conveys the recording paper P, a fixing device 47 that fixes the toner image on the recording paper P, and a discharge that discharges the recording paper P on which the toner image has been fixed to the outside of the apparatus main body. A paper roller 48 and a paper discharge tray 49 for stacking and storing the discharged recording paper P are disposed. Note that details of the image forming process are the same as those of a conventionally known technique, and are omitted.

  Next, the toner supply unit will be described in detail. 3 is a perspective view of the toner replenishing portion 5, FIG. 1 is a perspective view of the second developer accommodating portion 50, FIG. 4 is a perspective view of the developer accommodating portion, and FIG. It is a perspective view of the state which removed the near side cover (a part of pipe). As shown in the main section of the printer in FIG. 2, four toner replenishing sections 5 are arranged above the printer main body corresponding to each of Y, M, C, and Bk colors.

  Next, since each color of each toner replenishing unit has the same configuration, M will be described as an example. The cylindrical toner bottle 51M stores magenta toner, which is rotated by a driving unit (not shown), and the stored magenta toner is discharged to the developer container 52. The developer container 52 includes an agitator 53 and a discharge screw 54. When the discharge screw 54 is rotated by a driving unit (not shown), the toner is discharged from a discharge port 55 provided at the front end portion of the developer container 52. The discharged toner enters the transport pipe portion 56 from the receiving port 56a, is transported by the internal transport screw 57, and is sent from the discharge port 56b to the second developer accommodating portion 50. As shown in FIGS. 6 and 7, the second developer accommodating portion 50 includes an agitating member 57 and a replenishing screw 58, and toner entering from the toner receiving port 58 is in a toner accommodating chamber 60 in which the agitating member 57 is disposed. And is supplied to the developing device 23 from the supply port 61 by the replenishment screw 58 as appropriate according to the toner consumption of the developing device. A toner remaining amount detection sensor 62 is disposed on the wall surface of the storage chamber 60, and toner is supplied from the developer storage section 52 through the transport pipe section 56 so that the toner is filled up to this sensor position. Further, a part of the wall surface of the storage chamber 60 has an elastic wall surface portion 63 made of an elastic material. In this embodiment, an EPDM rubber having a thickness of 0.8 mm is used, but the invention is not limited to this, and urethane or the like may be used.

As described above, the conveying screw 57 conveys and supplies the toner to the second developer accommodating portion 50, and the toner is transferred by the rotation of the conveying screw 57. Since the replenishing screw 58 of the second developer container 50 rotates in response to a request from the downstream developing device 23, it may be stopped when the conveying screw 57 rotates. That is, in the second developer storage unit 50, air is sent into the storage chamber 60 from the upstream side by the transport screw 57 with the downstream side blocked in a series of toner transport paths. At this time, the pressure in the storage chamber 60 becomes higher than the external atmospheric pressure, but the elastic body surface portion 63 is deformed outward, whereby the volume of the storage chamber 60 increases and the rise in pressure is alleviated. In this embodiment, the volume of the storage chamber 60 excluding the stirring member 59 is 82 cm ³ , and the remaining space when the toner is filled up to the toner remaining amount detection sensor 62 is 29 cm ³ , and is fed at once by the conveying screw 57. The toner and air used are 5 cm ³ . In the absence of the elastic wall portion 63, the pressure fluctuation in the storage chamber 60 was 12 kPa. However, the pressure fluctuation in this embodiment is 5 kPa, reducing the pressure fluctuation range by 60%, and bleeding of toner from the joint portion. It was confirmed that there was no discharge and that stable toner conveyance and supply could be performed.

(Example 2)
Next, a second embodiment of the present invention will be described with reference to the drawings.

  FIG. 8 is a perspective view of the second developer accommodating portion 50 ′ for explaining the second embodiment. In addition, about the component which has a function similar to the component demonstrated in Embodiment 1, the same code | symbol is attached and the description is abbreviate | omitted.

  The printer main body 1 as the image forming apparatus according to the present embodiment is different from the first embodiment in the configuration of the second developer accommodating portion. The second developer accommodating portion 50 ′ shown in FIG. 8 is configured by arranging bellows-like bellows 64 on the wall surface of the accommodating chamber 60. The bellows 64 is telescopic, communicates with the storage chamber 60, and gives an effect of increasing the volume in the storage chamber 60 when the toner is replenished by the conveying screw 57. To ease.

  In this embodiment, the bellows 64 is molded from polyethylene, but it may be urethane. Further, the bellows 64 may be kept in a compressed state when the replenishment operation is not performed by the conveying screw 57 by a weight such as a steel plate or a spring bias on the upper portion 64a of the bellows 64. Needless to say, the mass of the weight and the biasing force of the spring bias are appropriately selected in consideration of pressure fluctuations and the force required to extend the bellows 64.

(Example 3)
Next, a third embodiment of the present invention will be described with reference to the drawings.

  FIG. 9 and FIG. 10 are perspective views of the vicinity of the receiving port 56a and the vicinity of the discharge port 56b of the transport pipe portion 56 for explaining the third embodiment. In addition, about the component which has a function similar to the component demonstrated in Embodiment 1, the same code | symbol is attached and the description is abbreviate | omitted.

  As shown in FIGS. 9 and 10, holes 57a and 57b are formed in the vicinity of the receiving port 56a side and in the vicinity of the discharge port 56b side of the conveying screw 57 ′ installed in the conveying pipe 56, and between these holes, the holes of the conveying screw 57 ′ are formed. The shaft is communicated in the form of a hollow pipe. By communicating these holes 57a and 57b, when the pressure inside the second developer accommodating portion 50 increases, the air moves from the hole 57a to the hole 57b, and the increase in pressure can be reduced.

  By providing the holes 57a and 57b in the vicinity of both ends of the conveying screw 57 ', the toner does not reach a large amount and the holes are not clogged, but the holes 57a are more reliably prevented from clogging. , 57b may be provided with a filter that captures toner and allows only air to pass through.

  In this embodiment, the shaft portion of the conveying screw is hollow and communicated. However, the present invention is not limited to this. For example, a communication tube is separately provided so as to be parallel to the conveying pipe, and the second developer is accommodated. You may make it communicate with a part.

Example 4
Next, a fourth embodiment of the present invention will be described with reference to the drawings.

  FIG. 11 is a perspective view of the second developer accommodating portion 50 ″ for explaining the fourth embodiment. Note that components having the same functions as the components explained in the first embodiment are the same. The description is omitted.

  The printer main body 1 as the image forming apparatus according to the present embodiment is different from the first embodiment in the configuration of the second developer accommodating portion. 11 has a filter 65 disposed on the wall surface of the storage chamber 60. When the toner is replenished by the conveying screw 57, the air in the storage chamber 60 escapes to the outside. The pressure fluctuation in the storage chamber 60 is reduced.

  In this example, a PTFE (polytetrafluoroethylene) stretched sheet filter having a pore diameter of 3 μm was used. The hole diameter is smaller than the toner particle diameter, and is preferably 2/3 or less to prevent clogging of the filter. Moreover, in order to suppress the pressure fluctuation in the storage chamber 60, the air permeability (measurement according to JIS-P8117) is preferably 5 sec or less.

In this embodiment, the volume of the storage chamber 60 excluding the stirring member 57 is 82 cm ³ , and the remaining space when the toner is filled up to the toner remaining amount detection sensor 62 is 29 cm ³ . The present invention is particularly effective when the volume is small, that is, when the pressure fluctuation in the storage chamber increases due to the toner replenishment operation. However, the present invention is not limited to this, and the storage chamber has a large volume. It is also applicable to.

FIG. 6 is a perspective view of a second developer accommodating portion according to Embodiment 1 of the present invention. 1 is a schematic overall sectional view of a printer according to an embodiment of the present invention. FIG. 3 is a perspective view of a toner supply unit according to the first exemplary embodiment of the present invention. FIG. 3 is a perspective view of a developer accommodating portion according to Embodiment 1 of the present invention. The perspective view of the conveyance pipe part which concerns on Example 1 of this invention. FIG. 6 is a schematic cross-sectional view of a second developer accommodating portion according to Embodiment 1 of the present invention. FIG. 6 is a schematic cross-sectional view of a second developer accommodating portion according to Embodiment 1 of the present invention. FIG. 10 is a perspective view of a second developer accommodating portion according to Embodiment 2 of the present invention. The fragmentary perspective view of the conveyance pipe part which concerns on Example 3 of this invention. The fragmentary perspective view of the conveyance pipe part which concerns on Example 3 of this invention. FIG. 10 is a perspective view of a second developer accommodating portion according to Embodiment 4 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer main body 2 Image formation part 20 Photosensitive drum 23 Developer 50, 50 ', 50 "2nd developer accommodating part 52 Developer accommodating part 56 Conveying pipe part 56a Inlet 56b Outlet 57, 57' Conveying screw 57a, 57b Hole 58 Replenishing screw 58 Stirring member 60 Toner storage chamber 61 Supply port 62 Remaining toner detection sensor 63 Elastic wall surface portion 64 Bellows 65 Filter

Claims (10)

The developer transported in the middle of the developer transport path between the developing device that develops the latent image on the photosensitive member and the first developer storage portion that stores the developer to be supplied to the developing device is temporarily stored. In the image forming apparatus provided with the second developer containing portion having a supply means for supplying the developer according to the developer consumption of the developing device,
An image forming apparatus, wherein a part of a container wall surface of the second developer accommodating portion is formed of a deformable elastic portion. The developer transported in the middle of the developer transport path between the developing device that develops the latent image on the photosensitive member and the first developer storage portion that stores the developer to be supplied to the developing device is temporarily stored. In the image forming apparatus provided with the second developer containing portion having a supply means for supplying the developer according to the developer consumption of the developing device,
An image forming apparatus, wherein a member for forming a volume-variable space is provided in a part of a container wall surface of the second developer accommodating portion. 3. The image forming apparatus according to claim 1, further comprising means for urging the elastic body portion or the space having a variable volume in a direction in which a storage volume of the second developer storage portion decreases. The developer transported in the middle of the developer transport path between the developing device that develops the latent image on the photosensitive member and the first developer storage portion that stores the developer to be supplied to the developing device is temporarily stored. In the image forming apparatus provided with the second developer containing portion having a supply means for supplying the developer according to the developer consumption of the developing device,
In addition to the developer transport path, the image forming apparatus includes a communication pipe that communicates the first developer accommodating portion and the second developer accommodating portion. The image forming apparatus according to claim 4, wherein the communication pipe is a pipe in which a shaft portion of a developer transport screw in the developer transport path for transporting the developer is formed into a hollow shape. 6. The image forming apparatus according to claim 4, wherein a filter that captures the developer and has air permeability is disposed at a joint portion of the connecting pipe with the second developer accommodating portion. The developer transported in the middle of the developer transport path between the developing device that develops the latent image on the photosensitive member and the first developer storage portion that stores the developer to be supplied to the developing device is temporarily stored. In the image forming apparatus provided with the second developer containing portion having a supply means for supplying the developer according to the developer consumption of the developing device,
An image forming apparatus, wherein a filter that captures the developer and has air permeability is disposed on a part of the container wall surface of the second developer accommodating portion. 8. The image forming apparatus according to claim 6, wherein the pore size of the filter is 2/3 or less of the particle size of the developer and the air permeability (Gurley number) is 5 [sec] or less. The image forming apparatus according to claim 1, wherein a volume of the developer accommodating portion of the second developer accommodating portion is 200 cm ³ or less. A developer remaining amount detection sensor is provided in the second developer container, the powder surface position of the developer is maintained within a predetermined range, and the volume of the developer-free space in the volume of the developer container The image forming apparatus according to claim 9, wherein the image forming apparatus is 50 cm ³ or less.

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