JP3556074B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus using an electrophotographic method for forming a toner image by electrostatically attaching toner on an image carrier such as a photoconductor, such as a copying machine, a printer, a facsimile, and a multifunction machine thereof. .
[0002]
[Prior art]
Conventionally, in this type of image forming apparatus, in response to recent demands for effective use of resources and environmental conservation, untransferred toner remaining on the image carrier is collected by a cleaning device, and the developing device is re-used as recycled toner. There is a toner recycling type which is returned to the inside and reused.
[0003]
For example, as shown in FIG. 3, there is a device provided with a toner recycling device 5 that connects a cleaning device 1 and a toner hopper 2a provided above the developing device 2 with a recycling pipe 4 in which a screw conveyor 3 is disposed. .
[0004]
At the time of image recording, the untransferred toner on the photoreceptor 6 is scraped off by the cleaning blade 1a of the cleaning device 1, collected in the case 1b, and conveyed to the near side in the case 1b by a conveying coil (not shown). Then, the toner is conveyed through the recycling pipe 4 by the screw conveyor 3 and returned into the toner hopper 2a.
[0005]
Among other things, the other end of the recycle pipe 4 having one end connected to the cleaning device 1 is extended toward the toner supply port 7 provided on the bottom side of the developing device 2 as shown in FIG. In some cases, the collected toner conveyed through the recycling pipe 4 is dropped from the toner supply port 7 and returned directly to the developing chamber 2b by the conveying coil 8.
[0006]
[Problems to be solved by the invention]
However, in such a conventional image forming apparatus, extra stress is applied to the collected toner by the screw conveyor 3 and the conveyance coil 8 during the conveyance of the collected toner, and the collected toner is aggregated due to the extra stress, resulting in a large foreign matter. And is sent into the developing device 2. Such a lump of foreign matter scatters from the inside of the developing device 2 arbitrarily and adheres to the background portion of the photoreceptor surface due to a small charge amount, and as a result, black spots or the like appear on the background portion of the recorded paper. There has been a problem that image quality has deteriorated.
[0007]
[Means for Solving the Problems]
Therefore, according to the first aspect of the present invention, an image carrier such as a photoconductor 10 is rotated as shown in the following embodiment, and when the image carrier passes a developing position, toner is applied to the surface thereof. An electrophotographic image forming apparatus that electrostatically develops an electrostatic latent image adhered and formed on an image carrier with toner while reusing untransferred toner as recycled toner , wherein the developing position The turbulence generators 30a to 30c are provided near the surface of the image carrier at a downstream position of the turbulence generators 30a to 30c around which the turbulence generators 30a to 30c generate turbulence. A turbulence generator 30 for removing foreign matter t adhered to the surface of the image carrier is provided separately from the developing device 12.
[0008]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, for example, as shown in the following embodiment, foreign matter t removed from the image carrier by the turbulence generating units 30a to 30c. Receiving, a foreign substance receiver 31 is provided.
[0009]
According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, for example, as described in the following embodiment, the turbulence generating sections 30a to 30c are formed of a conductive material and grounded. , Is characterized.
[0010]
Then, at the time of image recording, the foreign matter t removed from the image carrier is prevented from electrostatically adhering to the turbulence generating units 30a to 30c.
[0011]
According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, for example, as shown in the following embodiment, a plurality of the turbulence generating units 30a to 30c are provided in a rotation direction of the image carrier. It is characterized by being provided.
[0012]
According to a fifth aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein a gap g between the turbulence generating units 30a to 30c and the image carrier is provided, for example, as shown in the following illustrated embodiments. Is set to 0.5 mm or less.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 shows a schematic configuration of an image forming unit in an image forming apparatus according to an embodiment of the present invention.
[0014]
In the figure, reference numeral 10 denotes a drum-shaped photoconductor (image carrier) having a diameter of 100 mm. Around the photoconductor 10, a developing device 12, a transfer device 13, and a cleaning device 14 are provided in order from the charging device 11 provided above the photoconductor 10 in the rotation direction (clockwise direction in the figure) of the photoconductor 10. Further, a fixing device 15 is provided on the left side of the cleaning device 14 in the drawing, and a laser writing device 16 is provided above the charging device 11.
[0015]
During image recording, the photoconductor 10 is rotated in the direction indicated by the arrow in FIG. 2, while paper is fed out of a paper cassette ( not shown), and the paper P is conveyed to the lower side of the photoconductor 10 at a certain timing. .
[0016]
As the photoreceptor 10 rotates, first, the surface is uniformly charged by a charging device 11, and the surface is irradiated with a laser beam L by a laser writing device 16 to perform writing. Form a latent image. Then, when the toner passes through the position of the developing device 12, a developing bias is applied to the developing sleeve 18 to electrostatically adhere the toner, and the latent image on the photoconductor 10 is visualized. Then, the visible image is transferred by the transfer device 13 to the sheet P conveyed below the photoconductor 10. Then, the transferred paper P is conveyed to the fixing device 15, where the toner image on the paper P is fixed by applying heat and pressure, for example, and then discharged to a discharge stack unit (not shown).
[0017]
On the other hand, the surface of the photoreceptor 10 after image transfer is cleaned by scraping off the untransferred toner remaining on the surface with the cleaning blade 19 of the cleaning device 14 to prepare for reuse.
[0018]
The image forming apparatus further includes a toner recycling device indicated by reference numeral 20 in front of the image forming unit in FIG.
[0019]
In the toner recycling device 20, a transport pipe 22 is connected to the bottom of the toner recovery case 21 of the cleaning device 14 on the near side in FIG. 2 downward, and an air pump 24 is connected to a lower end of the transport pipe 22. Further, the lower end of the recycling pipe 25 is connected to the air pump 24, and the upper end is connected to a toner hopper 26 provided above the developing device 12.
[0020]
A collection coil 27 is rotatably provided at the bottom of the toner collection case 21, and a conveyance coil 23 is rotatably provided within the conveyance pipe 22.
[0021]
In this image forming apparatus, the untransferred toner scraped off from the photoreceptor 10 during the above-described cleaning is transported in the toner recovery case 21 to the near side in FIG. It falls into the air pump 24 through the transport pipe 22. Then, the toner is pushed up through the recycling pipe 25 by the air pump 24 and is conveyed to the toner hopper 26, and is sent into the toner hopper 26 as recycled toner.
[0022]
The recycled toner is stirred by the rotary stirring member 28 in the toner hopper 26 and mixed with the new toner, and if necessary, is supplied to the developing chamber 12a by rotating the supply roller 29, and is reused for development.
[0023]
In the image forming apparatus, during the conveyance of the collected toner, stress is applied to the collected toner by the collection coil 27, the conveyance coil 23, and the like, and the collected toner is aggregated to form a mass of large foreign matters, thereby developing the image. It may return to the room 12a. Then, the lump of the foreign matter may be scattered from the developing chamber 12a and adhere to the background on the photoreceptor 10.
[0024]
Therefore, in order to remove the foreign matter from the photoreceptor 10, the image forming apparatus of the present invention includes a turbulence generator 30 which is longitudinal in the axial direction of the photoreceptor 10 at a position downstream of the developing position as shown in FIG. Provide.
[0025]
The turbulence generator 30 is provided with a foreign object receiver 31 made of, for example, an elongated conductive metal plate. Then, as shown in FIG. 1, two conductive metal plates having a thickness of 0.2 mm are erected on the foreign substance receiver 31 and fixed by welding or the like. Then, the two metal plates and the bent convex portion 31a on the left side edge of the foreign object receiver 31 in the drawing form three turbulent flow generating portions 30a, 30b, and 30c having different heights, and these are formed. formed by upright in parallel to each other at equal intervals of approximately 1 mm.
[0026]
The turbulence generator 30 sequentially forms the turbulence generators 30a, 30b, and 30c in the rotation direction of the photoconductor 10, and at a position where each end is close to the surface of the photoconductor 10, for example, not shown. Attach it to the side plate and support it. In this case, a gap g of 0.5 mm or less is provided between the turbulence generators 30a, 30b, and 30c and the photoconductor 10. In the illustrated embodiment, the gap g is approximately 0.3 mm. Although not shown, the turbulence generators 30a, 30b, and 30c are grounded via, for example, the side plates.
[0027]
When the photoreceptor 10 rotates during the above-described image recording, air around the surface of the photoreceptor 10 flows in a laminar flow state as shown by an arrow A in FIG. Then, when the laminar flow A hits the turbulence generators 30a, 30b, and 30c at a position downstream of the developing position, a turbulence is generated there.
[0028]
At this time, if the above-described foreign matter has adhered to the photoreceptor 10, the foreign matter is not electrostatically adhered to the photoreceptor 10, and is separated from the surface of the photoreceptor 10 by turbulence. Fall. Then, the foreign matter t falling from the photoconductor 10 is received and collected by the foreign matter receiver 31.
[0029]
Further, since the turbulence generators 30a, 30b, and 30c are grounded, the foreign matter t falling from the photoconductor 10 does not electrostatically adhere to the turbulence generators 30a, 30b, and 30c during the fall. , Falls on the foreign object receiver 31 as it is. On the other hand, since the toner of the toner image formed on the photoconductor 10 is electrostatically attached to the photoconductor 10, it is not separated from the photoconductor 10 by turbulence.
[0030]
In the illustrated embodiment described above, when 10,000 images are recorded, the lump of the foreign matter t generated during the recycling of the toner does not appear on the background of the recorded paper as black spots or the like. It was confirmed that the particles were collected on the foreign substance receiver 31.
[0031]
【The invention's effect】
Therefore, according to the first to fifth aspects of the present invention, the foreign matter adhering to the surface of the image carrier is removed by generating a turbulent flow in the turbulence generating section when the image carrier rotates. Can be prevented from appearing as black spots or the like on the ground portion of the recorded paper, and the image quality can always be kept good.
[0032]
According to the second aspect of the present invention, in addition, the foreign matter removed from the image carrier in the turbulence generating section can be received and collected by the foreign matter receiver, so that the removed foreign matter stains the inside of the image forming apparatus. Can be prevented.
[0033]
According to the third aspect of the present invention, in addition, since the turbulence generating portion is formed of a conductive material and grounded, it is possible to prevent foreign matter from electrostatically adhering to the turbulence generating portion during removal. Accordingly, foreign matters can be more effectively removed from the image carrier.
[0034]
According to the fourth aspect of the present invention, in addition, since a plurality of turbulence generating portions are provided in the rotation direction of the image carrier, the turbulence generating portions generate turbulence around the image carrier at a plurality of locations. As a result, foreign substances adhering to the image carrier can be more reliably removed.
[0035]
According to the fifth aspect of the present invention, in addition, the gap between the turbulence generating unit and the image carrier is set to 0.5 mm or less, and the turbulence generating unit is appropriately spaced from the image carrier. The turbulence generating section can generate an effective turbulent flow around the image carrier when the image carrier is rotated, thereby adhering to the image carrier. Foreign matter can be efficiently removed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a state in which a turbulence generator removes foreign matter from a photoreceptor in an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of an image forming unit of the image forming apparatus.
FIG. 3 is a longitudinal sectional view showing a toner recycling mechanism provided in a conventional image forming apparatus.
FIG. 4 is a longitudinal sectional view showing a toner recycling mechanism provided in another conventional image forming apparatus.
[Explanation of symbols]
10 Photoconductor (image carrier)
30 turbulence generators 30a to 30c turbulence generator 31 foreign matter receiver P paper g gap t foreign matter

Claims (5)

When the image carrier rotates, the toner adheres to the surface of the image carrier when the image carrier passes a developing position, and the electrostatic latent image formed on the image carrier is electrostatically developed with the toner. In an image forming apparatus using an electrophotographic method in which toner is reused as recycled toner, a turbulence generating unit is provided near a surface of the image carrier at a position downstream of the developing position, and when the image carrier rotates. An image forming apparatus including a turbulence generator separately from the developing device for generating turbulence around the turbulence generator and removing foreign matters adhered to the surface of the image carrier. 2. The image forming apparatus according to claim 1 , further comprising a foreign matter receiver configured to receive the foreign matter removed from the image carrier by the turbulence generating unit. 3. The image forming apparatus according to claim 1, wherein the turbulence generator is formed of a conductive material and grounded. The image forming apparatus according to claim 1, wherein a plurality of the turbulence generating units are provided in a rotation direction of the image carrier. The image forming apparatus according to claim 1, wherein a gap between the turbulence generating unit and the image carrier is set to 0.5 mm or less.

Images