JP2005084557A - Toner scattering preventing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent failures such as clogging of a tube connected to an air discharge means, clogging of a filter and a pump malfunction. <P>SOLUTION: In the toner scattering preventing device for an image forming apparatus equipped with a two-component developing apparatus 14 using developer constituted of non-magnetic toner and magnetic carrier, the air discharge means 72 for sucking the air inside the developing apparatus 14 through a suction tube 71 and discharging the air through a discharge tube 73 is installed, and a magnet 200 for scavenging the carrier is arranged at the entrance part of the suction tube 71. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a toner scattering prevention device and an image forming apparatus.

In an electrophotographic image forming apparatus, fine powder toner is used in a developing device. If the toner scatters in the machine, the paper passing through the machine is soiled, and various types of toner scatter prevention devices have been proposed. As a conventional technique for preventing toner scattering, an apparatus provided with air suction means from the inside of a developing device is described in, for example, Patent Document 1 and others.
Japanese Patent Laid-Open No. 10-3220

However, when the two-component developer composed of toner and carrier is sucked in air from the developing device, the carrier repelled by stirring may be sucked. Since the sucked carrier is heavier than the toner, it accumulates in the middle of the exhaust path or in the exhaust means, and may cause problems such as clogging the tube or the like, or clogging the filter. Further, since the toner is accumulated in the collection tank as the toner storage means, it is quickly filled and needs to be replaced, and the maintenance interval is shortened.
An object of the present invention is to prevent problems such as tube clogging, filter clogging, pump failure and the like connected to the exhaust means.

In order to achieve the above object, the invention described in claim 1 is a toner scattering prevention device in an image forming apparatus provided with a two-component developing device using a developer composed of a non-magnetic toner and a magnetic carrier, The most important feature is a toner scattering prevention device provided with exhaust means for sucking air in the developing device through the intake tube and exhausting it through the exhaust tube, and providing a magnet for collecting the carrier at the inlet portion of the intake tube.
According to a second aspect of the present invention, there is provided a toner scattering prevention device in an image forming apparatus provided with a two-component developing device using a developer composed of non-magnetic toner and a magnetic carrier, and the air in the developing device is sucked into an intake tube. To prevent toner scattering by providing exhaust means for suctioning through the exhaust tube and toner collection means for collecting toner from the air exhausted by the exhaust means, and providing a magnet for collecting the carrier at the inlet of the intake tube The device is the main feature.
According to a third aspect of the present invention, there is provided a toner scattering prevention device in an image forming apparatus provided with a two-component developing device using a developer composed of non-magnetic toner and a magnetic carrier, wherein the air in the developing device is sucked into an intake tube. And the toner collecting means for collecting the toner from the air exhausted by the exhaust means, and the toner collecting means located upstream of the toner collecting means. The most important feature is a toner scattering prevention device provided with toner storage means for storing toner without falling into the toner of the developing device, and provided with a magnet for collecting the carrier at the inlet of the intake tube.
According to a fourth aspect of the present invention, there is provided a toner scattering prevention device in an image forming apparatus provided with a two-component developing device using a developer comprising non-magnetic toner and a magnetic carrier, wherein the air in the developing device is sucked into an intake tube. And the toner collecting means for collecting the toner from the air exhausted by the exhaust means, and the toner collecting means located upstream of the toner collecting means. A toner storing means for storing the toner without falling into the toner of the developing device and a toner recycling means for returning the toner stored in the toner storing means to the developing device and reusing them are provided, and the carrier is collected at the inlet tube inlet. The most important feature is a toner scattering prevention device provided with a magnet.
According to a fifth aspect of the present invention, an image forming apparatus including the toner scattering prevention device according to any one of the first to fourth aspects is the main feature.

  According to the present invention, since the magnet for collecting the carrier is provided at the inlet portion of the intake tube, the intended object can be achieved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall schematic configuration of a laser copying machine provided with a toner scattering preventing device according to the present invention. FIG. 2 shows a partially enlarged configuration of the main part.
Reference numeral 10 in the figure denotes an image forming apparatus main body. A drum-shaped image carrier 12 is provided in the apparatus main body 10. Around the image carrier 12, a charging device 13, a developing device 14, a transfer / conveyance device 15, a cleaning device 16, a static elimination device 17, and the like are arranged.
On top of them, a laser writing device 18 is provided. The laser writing device 18 includes a light source 20 such as a laser diode, a scanning rotary polygon mirror 21, a polygon motor 22, a scanning optical system 23 such as an fθ lens, and the like.
A fixing device 25 is disposed on the left side of the cleaning device 16 in the drawing. The fixing device 25 is provided with a fixing roller 26 incorporating a heater and a pressure roller 27 that presses against the fixing roller 26 from below.
A document reading device 30 is provided in the upper part of the apparatus main body 10. The document reading device 30 is provided with a light source 31, a plurality of mirrors 32, an imaging lens 33, an image sensor 34 such as a CCD.
On the other hand, a duplex unit 35 is provided in the lower part of the apparatus main body 10. A re-feeding path 37 is provided from the duplex unit 35 to the feeding path 36 extending downward from the image carrier 12. The duplex unit 35 is branched from the middle of the sheet discharge path 38 extending from the outlet of the fixing device 25 to form a reverse path 39.
A contact glass 40 is installed on the upper surface of the apparatus main body 10. An automatic document feeder 41 is mounted on the apparatus body 10 so as to be openable and closable so as to cover the contact glass 40.
By the way, the image forming apparatus main body 10 as described above is placed on the paper feed table 43. In the paper feed table 43, paper feed cassettes 44 are provided in multiple stages. Each paper feed cassette 44 is provided with a corresponding paper feed roller 45. The sheet feeding roller 45 puts the fed sheet into a conveyance path 46 that leads to the sheet feeding path 36. A plurality of pairs of conveyance rollers 47 are provided in the conveyance path 46.

When taking a copy using this laser copying machine, the original is set on the automatic document feeder 41 or the automatic document feeder 41 is opened and the original is directly set on the contact glass 40. Then, a start switch (not shown) is pressed and the automatic document feeder 41 is driven to feed a document conveyed on the contact glass 40 or a document set in advance on the contact glass 40 with the document reading device 30. Read in units.
At the same time, an appropriate paper feed roller 45 is rotated to feed out the sheet from the corresponding paper feed cassette 44 among the plurality of paper feed cassettes in the paper feed table 43, put into the transport path 46, and transported by the transport roller 47, The sheet is put in the sheet feed path 36 and is abutted against the registration roller 48 and stopped. Then, the registration roller 48 is rotated in synchronization with the rotation of the image carrier 12, and is sent below the image carrier 12.
On the other hand, when a start switch (not shown) is pressed, the image carrier 12 is simultaneously rotated clockwise in the drawing. Then, along with the rotation of the image carrier 12, the surface is first uniformly charged by the charging device 13, and then the laser writing device 18 is irradiated with the laser light L according to the reading content read by the document reading device 30 described above. Then, writing is performed to form an electrostatic latent image on the surface of the image carrier 12, and then the toner is attached by the developing device 14 to make the electrostatic latent image visible.
Then, as described above, the visible image is transferred by the transfer / conveyance device 15 to the sheet fed below the image carrier 12. The surface of the image carrier 12 after the image transfer is cleaned by removing the residual toner with the cleaning device 16, and with the static eliminator 17, and preparing for subsequent image formation.
On the other hand, the image-transferred sheet is conveyed by the transfer / conveyance device 15 and put into the fixing device 25, and heat and pressure are applied by the fixing roller 26 and the pressure roller 27 to fix the transferred image. Thereafter, the paper is discharged through a paper discharge path 38 onto, for example, a tray (not shown) attached to the apparatus body 10.
When recording on the back side of the sheet using this copying machine, after recording on one side, it is put into the duplex unit 35 through the reverse path 39, reversed there, and sent again below the image carrier 12, separately. The image formed on the image carrier 12 is similarly transferred to the back surface, and then discharged onto a tray (not shown), for example.

The developing device 14 described above includes a developing tank 50 and a developing hopper 60 as can be seen from FIG.
In the developing tank 50, a first developing roller 51, a second developing roller 52, a paddle wheel 53, a stirring roller 54, a conveying screw 55, a separator 56, a doctor blade 57, a toner concentration sensor 58 and the like are provided in a developing case 59. In the developing case 59, a two-component developer composed of carrier and toner is stored.
In the developing hopper 60, a gear-shaped toner replenishing member 61, a replenishment regulating plate 62, an agitator 63, and the like are provided. The developing hopper 60 contains toner.
In the developing device 14, the two-component developer in the developing case 59 is stirred and frictionally charged by the rotation of the stirring roller 54, and is flipped up by the rotation of the paddle wheel 53. The first developing roller 51 and the second developing roller 52 are attracted by the magnet in the roller 52.
The developer adsorbed on the first developing roller 51 and the second developing roller 52 is conveyed by the sleeves on the outer periphery of the first developing roller 51 and the second developing roller 52 and scraped off the excess by the doctor blade 57. The electrostatic latent image on the image carrier 12 is developed by being attached to the image carrier 12 by a developing bias.

In the developing device 14, when the toner is attached to the image carrier 12 and consumed, the ratio (toner concentration) decreases. Therefore, when the toner concentration in the developer becomes equal to or lower than a predetermined value with respect to the target value of the toner concentration, the agitator 63 is rotated to stir the toner and transport the toner to the toner supply member 61. The toner supply member 61 is rotated. Then, the replenishment regulating plate 62 is swung to replenish toner from the developing hopper 60 into the developing tank 50 to maintain the toner concentration in the developer.
The toner concentration in the developer is measured by a toner concentration sensor 58 attached to the developing case 59. The target value of the toner density is set by a value obtained by measuring a measurement toner image (P pattern) created on the image carrier 12 with a photosensor.
In general, there are often no images on both sides of the sheet. Therefore, in order to prevent the amount of toner on both sides from increasing, toner is replenished from the developing hopper 60 in the toner replenishment region b excluding both sides.
Incidentally, as described above, the toner attached to the image carrier 12 is electrostatically transferred onto the sheet by the transfer / conveyance device 15. However, about 10% of the toner remains untransferred and remains on the image carrier 12. Residual toner that has not been transferred and remains on the image carrier 12 is scraped off from the image carrier 12 by a cleaning blade 65 and a brush roller 66 provided in the cleaning device 16.
The toner scraped off from the image carrier 12 by the cleaning device 16 enters the recovery tank 67 of the cleaning device 16. Then, the toner is conveyed to one side of the cleaning device 16 by the recovery screw 68, discharged from a discharge port (not shown), and guided to the toner recycling device.
As shown in FIG. 1, the illustrated laser copying machine includes a toner scattering prevention device 70 connected to the developing device 14. The toner scattering prevention device 70 is connected to the developing device 14 by an intake tube 71 and is provided with an exhaust means 72 in the apparatus main body 10. The exhaust means 72 and the exhaust tube 73 are connected to each other in the paper feed table 43. The toner storing means 74 is provided.
A suction duct 75 is attached to the tip of the intake tube 71 as shown in FIG. The suction duct 75 has an elongated rectangular shape, has a connection port 76 for connecting one end of the intake tube 71 at the center of the upper surface, and opens a large opening 77 on the lower surface as shown in FIG. However, a sheet member 78 such as mylar is attached to the lower surface of the developing hopper 60 so as to correspond to the toner replenishment region b to close the central portion of the opening 77, and suction ports 79 are provided only on both sides. Further, a seal member 80 is attached around the opening 77 except for the developing hopper 60 side. As will be described later, the suction duct 75 is connected to an opening provided in the developing device. In the claims, the tip of the intake tube is a concept including the suction duct 75.

In the suction duct 75 of the developing device of the present invention, as shown in FIG. 11, a magnet 200 is attached with a double-sided tape in the vicinity of the suction port 79 (the inner part of the suction port) serving as the exhaust port inlet. For this reason, even if the carrier is sucked together by air suction from the inside of the developing device by the toner scattering prevention device, it is attracted by the magnetic force of the magnet 200 provided at the inlet portion of the suction port 79, so that it is attracted from the inside of the developing device. I don't get out.
Therefore, the intake tube 71 and the exhaust tube 73 are not clogged with the carrier, and the carrier does not enter the exhaust means 72 and cause a failure. Further, clogging of the filter 100 (toner repairing means) can be prevented. Further, since the carrier does not enter the tank 97 (toner storage means), it is possible to prevent the tank 97 from becoming full at an early stage and to lengthen the replacement period of the tank 97.
The attachment position of the magnet 200 may be B or C in FIG. When affixed to the portion B, the suction duct 75 may be made of a nonmagnetic material. Similarly to the above, since the magnet 200 is in the suction port 79 portion, even if the carrier is sucked together by air suction, it is attracted to the magnet before reaching the intake tube 71 and is sucked out from the developing device. Therefore, the above-mentioned problem can be prevented.
As shown in FIG. 2, the suction duct 75 is an opening provided at both ends of the developing case 59 at appropriate positions in the upper direction of the developing case 59 by inserting the both ends of the suction duct 75 into guide grooves 82 provided opposite to both sides of the developing case 59. Attach to 83, and then attach the developing hopper 60 to the developing tank 50 to prevent it from coming off. A seal member 84 that seals between the suction duct 75 and the developing hopper 60 is attached. As a result, the opening 83 of the developing case 59 is completely closed.

Next, as shown in FIG. 5, the exhaust means 72 shown in FIG. 1 attaches the other end of the intake tube 71 to the intake port 87 of the pump 86 and attaches one end of the exhaust tube 73 to the exhaust port 88. Further, the eccentric pin 91 attached to the drive shaft 90 of the motor 89 is fitted to a part 93 of the rubber member 92.
Then, the motor 89 is driven in conjunction with a developing motor (not shown), and the motor 89 is driven to reciprocate the center of the rubber member 92 in the direction of the arrow in the figure, and the intake valve (not shown) is opened to open the exhaust (not shown). The valve is closed and the air in the developing device 14 is sucked in from the suction port 79 of the suction duct 75 described above, and is put into the pump 86 from the suction port 87 through the exhaust passage in the suction tube 71, or the exhaust valve is closed by closing the suction valve. Then, the air in the pump 86 is sent to the toner storing means 74 through the exhaust passage of the exhaust tube 73.
In this way, when the developing device 14 is operating, the exhaust means 72 is always driven and air in the developing device 14 is sucked in by the toner scattering prevention device 70 to suck in floating toner in the developing device 14. At the same time, a suction air flow is generated in the developing opening 95 of the developing case 59 shown in FIG. 2, and the surrounding air is sucked in, for example, as shown by an arrow a in FIG. Can do.
Even if the toner scattering prevention device 70 is not provided, the rotation of the developing rollers 51 and 52 generates an air current that sucks in ambient air from the developing opening 95. However, by providing the toner scattering prevention device 70, more air is sucked in. Thus, toner scattering from the developing device 14 can be further prevented.

As shown in FIG. 7, the toner storing means 74 is a tank 97 having a width and a height and a small depth, and is arranged outside of the paper feed table 43 along the conveyance path 46 as shown in FIG. . An inlet 98 for connecting the other end of the exhaust tube 73 is provided on one side of the upper surface, and an opening is provided at a slightly higher position on the outer surface. A large filter-like toner collecting means 100 is attached to the tank 97, and the opening is closed by the toner collecting means 100.
The toner collecting means 100 is obtained by drawing PTFE (polytetrafluoroethylene) having the highest chemical stability among fluororesins with a special technique to have a fine continuous porous structure, and allows air to pass therethrough. However, the toner is collected and stored in the tank 97.
In addition, when the expanded porous PTFE is used as the toner collecting means 100 as described above, even when air is applied while applying pressure, unlike other filters such as an electrostatic filter, there is no toner leakage and the toner is reliably collected. be able to.
As a result, the air sent from the exhaust means 72 through the exhaust tube 73 is put into the toner storage means 74, the toner is collected by the toner collection means 100, and the collected toner is stored in the tank 97 and collected. The collected air is discharged to the outside of the apparatus main body 10 through the exhaust grill.
The toner storage means 74 is provided with a toner full detection means (not shown) to detect toner fullness. When the toner is full, the toner in the tank 97 is discarded or the tank 97 is replaced with a new one.
Of course, the toner storing means 74 is not limited to the shape as shown in FIG. 7, and may have a shape as shown in FIG. 8, for example. The opening of the tank 97 and the toner collecting means 100 that closes the opening are preferably as large as possible so as not to be clogged. In FIG. 8, the reference numerals used in the corresponding parts in FIG. 7 are used as they are, and redundant explanations are omitted.
In the above-described example, the exhaust path is formed using the intake tube 71 and the exhaust tube 73, but naturally the exhaust path may be formed using not only the tube but also a pipe or the like.

By the way, in the illustrated example described above, the toner storing means 74 and the toner collecting means 100 are provided at the downstream position of the exhaust means 72. However, for example, as shown in FIG. 9, a toner storage unit 74 and a toner collecting unit 100 may be provided upstream of the exhaust unit 72.
In the illustrated example, the toner collected by the toner collecting means 100 is received by the tray-shaped toner storage means 74 without falling into the toner of the developing device 14. The toner storing means 74 is detachable so that the stored toner can be discarded, and the toner collected by the toner collecting means 100 can be easily processed.
In this way, the toner collected by the toner collecting means 100 can be stored in the upstream toner storing means 74 and the toner can be prevented from reaching the downstream exhaust means 72, so that the type of the exhaust means 72 is not limited. For example, an exhaust unit 72 using a fan 102 as shown in the figure may be used, and an optimal exhaust unit 72 is used in consideration of price, size, ease of assembly, and the like.
If the duct structure of the developing device of the present invention is used for the copying machine having this configuration, the carrier 100 is not sucked out from the developing device, so that the filter 100 (toner repairing means) can be prevented from being clogged. Further, since the carrier does not enter the toner storage means, it can be prevented from becoming full at an early stage, and the replacement or maintenance cycle of the toner storage means can be lengthened.

Further, for example, as shown in FIG. 10, a toner recycling unit 110 may be provided without discarding the toner. The illustrated toner recycling unit 110 forms a recess 104 in the toner storage unit 74 for collecting the stored toner, and a toner conveying member 105 such as a screw for bringing the toner to one side is provided in the recess 104, and the toner is brought to one side. For example, a toner recovery member 106 using a screw, a belt, a coil, or the like is provided to return the toner to the developing device 14, for example.
When the toner recycling unit 110 is provided, the toner collected by the toner collecting unit 100 can be recycled and the maintenance cost can be reduced.
If the duct structure of the developing device of the present invention is used for the copying machine having this configuration, the carrier is not sucked out from the developing device, so that the problem of the carrier clogging in the intake tube 71 and the like can be prevented. Further, when the load on the toner conveying member 105 such as a screw is increased due to the weight of the carrier, the toner conveying member itself is damaged, or the driving means of the toner conveying member is broken or damaged. These problems can be prevented.
Further, since the carrier is not mixed in the recycled toner, it is possible to prevent the toner replenishing member 61 of the developing hopper 60, the supply regulating plate 62, and other components of the developing hopper 60 from being broken or damaged.

1 is a laser copying machine including a toner scattering prevention device of the present invention, and is an overall schematic configuration diagram of an internal mechanism of the copying machine. FIG. 2 is a partially enlarged configuration diagram of a main part of FIG. 1. FIG. 3 is a perspective view of a suction duct attached to the tip of an intake tube that constitutes the toner scattering prevention device of the present invention. It is the perspective view which looked at the air intake duct of FIG. 3 from the lower surface side. FIG. 3 is an exploded perspective view of an exhaust unit constituting the toner scattering prevention device. FIG. 3 is a partially enlarged perspective view of the vicinity of a developing opening of a developing device in a laser copying machine. FIG. 4 is a perspective view of toner storage means that constitutes the toner scattering prevention device. FIG. 6 is a perspective view of another example of toner storage means. It is a block diagram of the other example of the toner scattering prevention apparatus used for a developing device. FIG. 10 is a configuration diagram of still another example of a toner scattering prevention device. It is sectional drawing of the air intake duct to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus main body, 12 Image carrier, 14 Developing apparatus, 59 Developing case, 70 Toner scattering prevention apparatus, 71 Intake tube, 72 Exhaust means, 73 Exhaust tube, 74 Toner storage means, 75 Suction duct, 79 Suction port, 86 pump, 95 development opening, 97 tank, 100 toner collecting means, 102 fan, 104 recess, 105 toner conveying member, 106 toner collecting member, 110 toner recycling means, 200 magnet, b toner supply area

Claims (5)

  A toner scattering prevention device in an image forming apparatus provided with a two-component developing device using a developer composed of a non-magnetic toner and a magnetic carrier, which sucks air in the developing device through an intake tube and exhausts it through an exhaust tube. An apparatus for preventing scattering of toner, characterized in that an exhausting means is provided, and a magnet for collecting a carrier is provided at an inlet of an intake tube.   A toner scattering prevention device in an image forming apparatus provided with a two-component developing device using a developer composed of a non-magnetic toner and a magnetic carrier, which sucks air in the developing device through an intake tube and exhausts it through an exhaust tube. And a toner collecting means for collecting toner from the air exhausted by the exhaust means, and a carrier collecting magnet is provided at an inlet of the intake tube.   A toner scattering prevention device in an image forming apparatus provided with a two-component developing device using a developer composed of a non-magnetic toner and a magnetic carrier, which sucks air in the developing device through an intake tube and exhausts it through an exhaust tube. Exhaust means for collecting toner, toner collecting means for collecting toner from the air exhausted by the exhaust means, and toner collected by the toner collecting means located upstream of the toner collecting means in the toner of the developing device And a toner storing means for storing without dropping, and a carrier collecting magnet is provided at an inlet portion of the intake tube.   A toner scattering prevention device in an image forming apparatus provided with a two-component developing device using a developer composed of a non-magnetic toner and a magnetic carrier, which sucks air in the developing device through an intake tube and exhausts it through an exhaust tube. Exhaust means for collecting toner, toner collecting means for collecting toner from the air exhausted by the exhaust means, and toner collected by the toner collecting means located upstream of the toner collecting means in the toner of the developing device Toner storage means for storing without falling, toner recycling means for returning the toner stored in the toner storage means to the developing device and reused, and providing a magnet for collecting the carrier at the inlet of the intake tube A toner scattering prevention device.   An image forming apparatus comprising the toner scattering prevention device according to claim 1.

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