JP4770886B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus for forming an image on a recording medium. Specifically, a paper dust removing roller for removing paper dust of the recording medium conveyed along the conveyance path is provided on the conveyance path of the recording medium. The present invention relates to an image forming apparatus provided.

2. Description of the Related Art Conventionally, in an image forming apparatus that forms an image on a recording medium, paper dust attached to the recording medium is prevented from adversely affecting the image formation. It has been proposed to provide a dust removing roller to remove paper dust from the recording medium. In this type of image forming apparatus, it has also been proposed to transport the paper dust removed by the paper dust removing roller to both ends in the paper width direction using an auger. In this case, the capacity of a tank or the like for storing the removed paper dust can be easily secured (see, for example, Patent Document 1).
JP 2005-41652 A

  However, in Patent Document 1, no countermeasure is taken against the paper dust removed by the paper dust removing roller falling again on the recording medium while being conveyed by the auger. Therefore, the present invention is such that the paper dust removed from the recording medium by the paper dust removing roller falls again on the recording medium while being conveyed in the direction along the rotation axis of the paper dust removing roller. An object of the present invention is to provide an image forming apparatus that can be satisfactorily suppressed.

  In order to achieve the above object, the present invention includes an image forming unit that forms an image on a recording medium, and a conveyance path through which the recording medium before the image is formed is conveyed toward the image forming unit. A paper dust removing roller that has a rotating shaft above the transport path and removes paper dust of the recording medium transported along the transport path, and a position above the rotational axis of the paper dust removing roller in the vertical direction. The paper dust on the paper dust removing roller is rotated by a rotation shaft that is opposed to the paper dust removing roller on the downstream side in the rotation direction of the paper dust removing roller and is arranged in parallel with the rotation shaft. A paper dust transporting means for transporting in a direction along each of the rotation shafts, and provided on the downstream side in the rotation direction of the paper dust removing roller with respect to the paper dust transporting means and above the transporting path; Contact with the surface of the dust removal roller It is characterized with scraping means for scraping the paper powder, further comprising a was.

  In the image forming apparatus of the present invention configured as described above, the transport path on which the recording medium before the image is formed is transported toward the image forming means has a rotating shaft above the transport path. A paper dust removing roller is provided for removing paper dust from the recording medium conveyed along the conveyance path. Then, the paper dust conveying means for conveying the paper dust on the paper dust removing roller in the direction along the rotation axis, and scraping off the paper dust attached to the surface of the paper dust removing roller in contact with the surface. The scraping means is arranged and configured as follows.

  In other words, the paper dust conveying means is opposed to the paper dust removing roller on the downstream side in the rotation direction of the paper dust removing roller from above in the vertical direction of the rotation axis of the paper dust removing roller, and is arranged in parallel with the rotation shaft. The paper dust is conveyed in the above-mentioned direction by rotating around the provided rotation shaft. Further, the scraping means is provided on the downstream side in the rotational direction of the paper dust removing roller and above the paper conveying path with respect to the paper dust conveying means, and is in contact with the surface of the paper dust removing roller. Scrape off paper dust adhering to the surface.

  That is, in the present invention, the paper dust conveying means and the scraping means are sequentially provided on the downstream side in the rotation direction of the paper dust removing roller from the vertical direction above the rotation axis of the paper dust removing roller. For this reason, the paper dust is scraped off at the downstream side in the rotation direction of the paper dust removing roller from the vertical direction above the rotation axis of the paper dust removing roller, and the vicinity thereof is conveyed in the direction along the rotation axis. Is done. Therefore, in the image forming apparatus of the present invention, the paper dust removed from the recording medium by the paper dust removing roller falls again onto the recording medium while being conveyed in the direction along the rotation axis of the paper dust removing roller. This can be suppressed satisfactorily.

  Although the present invention is not limited to the following configuration, the paper dust is provided on the upstream side of the paper dust conveying means in the rotation direction of the paper dust removing roller and faces the paper dust removing roller. May further include a backflow suppressing means for suppressing the backflow of the paper dust removing roller to the upstream side in the rotation direction. In this case, the backflow suppression means can suppress the backflow of the paper dust removed from the recording medium by the paper dust removal roller to the upstream side in the rotation direction of the paper dust removal roller from above the rotation shaft in the vertical direction. The paper powder can be more effectively prevented from falling on the recording medium.

  In this case, the backflow suppressing means may be configured such that the surface facing the paper dust removing roller is curved with a certain distance from the surface of the paper dust removing roller. In this case, a curved gap with a constant interval is formed between the surface of the paper dust removing roller and the opposite surface of the backflow suppressing means, so that the backflow of the paper dust removed from the recording medium by the paper dust removing roller is prevented. The paper powder can be suppressed more satisfactorily, and the paper powder can be further suppressed from dropping on the recording medium.

  In the image forming apparatus of the present invention, the paper powder conveying means and the paper dust removing roller may have opposite surfaces rotating in the same direction. In this case, the paper dust is transported to the downstream side in the rotation direction of the paper dust removing roller also by the rotation of the paper dust conveying means, so that the paper dust removed from the recording medium by the paper dust removing roller falls on the recording medium. This can be suppressed more satisfactorily.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing a schematic configuration of an image forming apparatus 1 to which the present invention is applied. In the following description, the left side in FIG. 1 is the front, and the near side in FIG. 1 is the right.

(Overall configuration of image forming apparatus)
The image forming apparatus 1 is a direct transfer tandem type color printer, and includes a substantially box-shaped housing 2 as shown in FIG. A front cover 3 is provided on the front surface of the housing 2. A paper discharge tray 5A on which paper 4 as a recording medium after image formation is stacked is formed on the upper surface of the housing 2, and the paper discharge tray 5A is provided integrally so that the image forming apparatus 1 is located upward. The top cover 5 is provided so as to be openable and closable around the upper rear end of the image forming apparatus 1. By opening the top cover 5, a belt unit 20 and an image forming unit 30 to be described later can be pulled out from the inside of the housing 2.

  A paper feed tray 7 that accommodates paper 4 for forming an image is attached to the lower portion of the housing 2 so as to be able to be drawn forward. In the paper feed tray 7, a pressure plate 9 is provided that can be tilted so as to stack and support the paper 4 and lift the front end side of the paper 4. In addition, a paper feed roller 11 that conveys the paper 4 is provided at a position above the front end of the paper feed tray 7. A separation roller 12 and a separation pad 13 are provided for separating the sheets one by one.

  The uppermost paper 4 in the paper feed tray 7 is separated one by one by the separation roller 12, and is further transported by being sandwiched between the first paper dust removing roller 14 and the opposing roller 15, and is fed to the sheet metal chute 18. It is guided and sent between the second paper dust removing roller 17 and the opposing roller 16. The second paper dust removing roller 17 (corresponding to an example of the paper dust removing roller) and the counter roller 16 function as a registration roller. After the front end of the paper 4 is locked, the paper 4 Is sent out onto the rear belt unit 20 at a predetermined timing.

  A part of the front cover 3 is configured to be openable as a manual feed tray 19 as shown in FIG. The paper 4 directly inserted by the user via the manual feed tray 19 is inserted between the second paper dust removing roller 17 and the opposing roller 16 through the opening 3 </ b> A of the front cover 3. The paper 4 inserted through the manual feed tray 19 in this way is also fed out onto the belt unit 20 by the second paper dust removing roller 17 and the opposing roller 16. That is, the path from the paper feed tray 7 or the manual feed tray 19 to the belt unit 20 corresponds to an example of a transport path.

  The belt unit 20 is attachable to and detachable from the housing 2, and includes a conveyor belt 23 installed horizontally between a belt driving roller 21 and a tension roller 22 that are spaced apart from each other in the front-rear direction. The transport belt 23 is an endless belt made of a resin material such as polycarbonate, and the paper placed on the upper surface thereof is circulated in the clockwise direction in FIG. 1 when the rear belt drive roller 21 is rotationally driven. 4 is conveyed backward.

(Configuration of image forming unit)
Inside the conveyance belt 23, four transfer rollers 24 arranged to face each photosensitive drum 31 included in the image forming unit 30 to be described later are provided at regular intervals in the front-rear direction, and correspond to each photosensitive drum 31. The transfer belt 24 is sandwiched between the transfer roller 24 and the transfer roller 24. At the time of transferring a toner image, which will be described later, a transfer bias is applied between the transfer roller 24 and the photosensitive drum 31, and a predetermined amount of transfer current is applied.

  Four image forming units 30 are provided corresponding to each color of black, cyan, magenta, and yellow in pairs with the LED unit 40, and the image forming unit 30 and the LED unit 40 are configured to convey paper. It is provided in series along the direction. The image forming unit 30, the LED unit 40, and the belt unit 20 corresponding to each color correspond to an example of an image forming unit.

  Each image forming unit 30 includes a photosensitive drum 31, a scorotron charger 32, a developing cartridge 34, and the like. The photosensitive drum 31 includes a grounded metal drum main body, and is configured by covering the surface layer with a positively chargeable photosensitive layer. The scorotron charger 32 is disposed opposite to the photosensitive drum 31 at a predetermined interval so as not to come into contact with the photosensitive drum 31 in the diagonally upper rear side of the photosensitive drum 31. The scorotron charger 32 uniformly charges the surface of the photosensitive drum 31 to positive polarity by generating corona discharge.

  The developing cartridge 34 has a substantially box shape, and a toner storage chamber 35 is provided in an upper portion thereof, and a supply roller 36, a developing roller 37, and a layer thickness regulating blade 38 are provided below the developing cartridge 34. . The toner storage chamber 35 of each developing cartridge 34 stores positively chargeable nonmagnetic one-component toner of each color of black, cyan, magenta, or yellow as a developer.

  The toner discharged from the toner storage chamber 35 is supplied to the developing roller 37 by the rotation of the supply roller 36, and is positively frictionally charged between the supply roller 36 and the developing roller 37. Further, the toner supplied onto the developing roller 37 enters between the layer thickness regulating blade 38 and the developing roller 37 with the rotation of the developing roller 37, and is further sufficiently frictionally charged here to have a constant thickness. It is carried on the developing roller 37 as a thin layer.

  The surface of the photosensitive drum 31 is first uniformly charged positively by the scorotron charger 32 when rotating. Thereafter, the LED unit 40 is exposed to LEDs (not shown) arranged in a row in the paper width direction (left-right direction) at the lower end of the LED unit 40, and an electrostatic latent image corresponding to the image to be formed on the paper 4 is formed. .

  Next, when the developing roller 37 rotates and the positively charged toner carried on the developing roller 37 comes into contact with and faces the photosensitive drum 31, a static image formed on the surface of the photosensitive drum 31 is formed. The electric latent image is supplied. As a result, the electrostatic latent image on the photosensitive drum 31 is visualized, and a toner image with toner attached only to the exposed portion is carried on the surface of the photosensitive drum 31.

  Thereafter, the toner image carried on the surface of each photosensitive drum 31 is transferred to the sheet by the transfer current when the sheet 4 conveyed by the conveying belt 23 passes between the photosensitive drum 31 and the transfer roller 24. 4 are sequentially transferred. The paper 4 on which the toner images of the respective colors are transferred in a superimposed manner is then conveyed to the fixing device 50.

  The fixing device 50 is disposed behind the conveyance belt 23 in the housing 2. The fixing device 50 includes a heating roller 51 that is rotationally driven with a heat source such as a halogen lamp, and a pressure roller 52 that is disposed below the heating roller 51 so as to face the heating roller 51 and is driven to rotate. It has. In the fixing device 50, the toner image is fixed to the paper 4 by heating the paper 4 on which the toner images of the respective colors are transferred while being nipped and conveyed by the heating roller 51 and the pressure roller 52. The sheet 4 on which the toner image is fixed is further conveyed by a conveying roller 53 disposed obliquely above and behind the fixing device 50, and is discharged by the discharge roller 54 provided on the upper portion of the housing 2. It is discharged onto the tray 5A.

(Configuration of paper dust collection unit)
Next, a paper dust collecting unit 70 that collects the paper dust collected from the paper 4 by the second paper dust removing roller 17 is provided above the second paper dust removing roller 17. Hereinafter, the configuration of the paper dust collecting unit 70 will be described. Note that the width of the first paper dust removing roller 14 is such that the surface of the sheet 4 separated by the separation roller 12 that is in contact with the separation pad 13 on the surface that contacts the separation pad 13 (the surface on which the toner image is transferred). It is formed slightly wider than the width of the separation pad 13 so as to remove powder. On the other hand, the width of the second paper dust removing roller 17 is formed slightly wider than the width of the paper 4 so as to remove the paper dust from the entire surface of the paper 4 on which the toner image is transferred.

  FIG. 2 is a side sectional view showing the configuration of the paper dust collecting unit 70 in detail. As shown by a one-dot chain line in FIG. 2, the rotation axis of the second paper dust removing roller 17 is disposed slightly behind the rotation axis of the opposing roller 16, and both rollers 17, 16 are indicated by arrows in FIG. As described above, the sheet 4 is conveyed backward by rotating the opposing surface in the same direction (backward).

  In addition, an auger 71 as an example of a paper dust conveying unit and a sponge 72 as an example of a scraping unit are sequentially arranged above the second paper dust removing roller 17 along the rotation direction. .

  The second paper dust removing roller 17 is configured by covering a metal roller shaft with a roller made of fluorine resin or the like whose surface is easily charged, while the sponge 72 charges the second paper dust removing roller 17. It is made of a resin material such as urethane foam. The second paper dust removing roller 17 that is frictionally charged by contact with the sponge 72 electrostatically adsorbs the paper dust adhering to the paper 4 when the paper 4 is sandwiched and conveyed between the opposing rollers 16. To do. Thereafter, the paper dust is scraped off from the surface of the second paper dust removing roller 17 by the sponge 72 in contact with the second paper dust removing roller 17. The first paper dust removing roller 14 is also provided with a sponge for electrostatically adsorbing paper dust, but is not shown in FIG.

  The auger 71 rotates the surface facing the second paper dust removing roller 17 in the same direction as the surface of the second paper dust removing roller 17 as shown by the arrow in FIG. It is a well-known thing comprised in the spiral shape conveyed toward both ends from. Further, as shown by a one-dot chain line in FIG. 2, the rotation axis of the auger 71 is arranged parallel to the rotation axis of the second paper dust removing roller 17 and slightly shifted forward from the rotation axis. In other words, the rotation shaft of the auger 71 is disposed on the downstream side in the rotation direction of the second paper dust removing roller 17 from above the rotation axis of the second paper dust removing roller 17 in the vertical direction. The auger 71 is formed longer in the paper width direction than the second paper dust removing roller 17, and tanks (not shown) in which paper dust conveyed to both ends in the paper width direction by the auger 71 are stored at both ends. Is provided.

  Above the second paper dust removing roller 17 and the auger 71, a cover 73 is provided as an example of a backflow suppressing means for covering them from above, and a surface 73A of the cover 73 facing the second paper dust removing roller 17 is The second paper dust removing roller 17 is curved along the surface. More specifically, the cover 73 has a facing surface 73A in a range from the vicinity of the rear end of the second paper dust removing roller 17 to the vicinity of the upper end (upstream in the rotational direction with respect to the portion facing the auger 71). A curved gap having a constant interval is formed between the facing surface 73A and the surface of the second paper dust removing roller 17.

  Further, a support member 75 made of an iron plate that supports the sponge 72 is attached to the base end portion 73B of the cover 73 with a slight backlash. The support member 75 is urged toward the second paper dust removing roller 17 by a pair of coil springs 76 provided at both ends in the paper width direction, and the sponge 72 causes the second paper dust removing to be urged by this urging force. The paper dust that is pressed against the surface of the roller 17 and adheres to the surface is scraped off. Then, the paper dust scraped off in this way is accumulated in the space around the auger 71 in the cover 73, and subsequently conveyed toward the both ends in the paper width direction by the auger 71 as described above.

  Note that the sponge 72 is deformed along the surface of the second paper dust removing roller 17 by the pressure contact as schematically shown in FIG. The entire sponge 72 is disposed above the conveyance path of the paper 4, more specifically, above the rotation shaft of the second paper dust removing roller 17, and the paper of the second paper dust removing roller 17 is arranged. It is provided over the entire width direction. Further, the coil spring 76 may be provided only at one end of the support member 75 in the sheet width direction or at the center in the sheet width direction.

(Effect and modification of this embodiment)
In the paper dust collecting unit 70 of the present embodiment configured as described above, the paper dust removed from the paper 4 by the second paper dust removing roller 17 is scraped off by the sponge 72, and then the paper is collected by the auger 71. It is conveyed toward both ends in the width direction. Here, since the auger 71 and the sponge 72 are provided on the downstream side in the rotation direction of the second paper dust removing roller 17 with respect to the vertical direction above the rotation axis of the second paper dust removing roller 17, the paper dust. Is again dropped on the paper 4 while being conveyed by the auger 71. That is, the paper dust dropped from the auger 71 during the transport is transported in the direction of the sponge 72 due to its own weight and the rotation of the second paper dust removing roller 17, and the paper dust is satisfactorily suppressed from falling onto the paper 4. be able to.

  In addition, in the present embodiment, a curved gap having a constant interval is formed between the facing surface 73A of the cover 73 and the surface of the second paper dust removing roller 17, as described above. It is possible to suppress the paper powder from flowing backward against the rotation of 17. Therefore, in the present embodiment, the paper dust can be more effectively suppressed from falling on the paper 4. In addition, when the space | interval of the opposing surface 73A of the cover 73 and the surface of the 2nd paper dust removal roller 17 is smaller than the diameter of the paper dust aggregated during the said conveyance, the fall of the said paper dust is suppressed further more favorably. be able to.

  In addition, this invention is not limited to the said embodiment at all, It can implement with a various form in the range which does not deviate from the summary of this invention. For example, as the paper dust conveying means, in addition to an auger, a coil spring, a brush with oblique hair transplantation, or the like can be applied. Moreover, in the said embodiment, although the opposing surface of the auger 71 and the 2nd paper dust removal roller 17 rotates in the same direction, the auger 71 may rotate in the reverse direction to the said embodiment. However, when the facing surfaces of the auger 71 and the second paper dust removing roller 17 rotate in the same direction as in the above embodiment, the paper dust is also rotated by the rotation of the second paper dust removing roller 17 by the rotation of the auger 71. It is conveyed downstream in the direction. For this reason, it is possible to better suppress the paper powder from flowing backward against the rotation of the second paper dust removing roller 17, and to further suppress the paper powder from falling on the paper 4. The present invention can be similarly applied to various image forming apparatuses other than those described above, such as a monochrome image forming apparatus and an inkjet printer.

1 is a side sectional view showing a schematic configuration of an image forming apparatus to which the present invention is applied. It is a sectional side view showing in detail the composition of the paper dust collection unit of the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 4 ... Paper 14 ... 1st paper dust removal roller 15 and 16 ... Opposite roller 17 ... 2nd paper dust removal roller 20 ... Belt unit 30 ... Image formation unit 31 ... Photosensitive drum 40 ... LED unit 70 ... Paper dust collecting unit 71 ... Auger 72 ... Sponge 73 ... Cover 73A ... Confronting surface 76 ... Coil spring

Claims (4)

Image forming means for forming an image on a recording medium;
A conveyance path through which the recording medium before the image is formed is conveyed toward the image forming unit;
A paper dust removing roller having a rotating shaft above the transport path and removing paper dust of the recording medium transported along the transport path;
The rotating shaft disposed opposite to the paper dust removing roller and in parallel with the rotating shaft is opposed to the paper dust removing roller on the downstream side in the rotation direction of the paper dust removing roller from above in the vertical direction of the rotating shaft of the paper dust removing roller. A paper dust conveying means for conveying the paper dust on the paper dust removing roller in a direction along each rotation axis by rotating to
Paper dust adhered to the surface of the paper dust removing roller, which is provided downstream of the paper dust conveying means in the rotational direction of the paper dust removing roller and above the conveying path, and contacts the surface of the paper dust removing roller. Scraping means for scraping,
An image forming apparatus comprising: It is provided on the upstream side in the rotation direction of the paper dust removing roller with respect to the paper dust conveying means and faces the paper dust removing roller, and the paper dust is prevented from flowing backward in the upstream direction in the rotation direction of the paper dust removing roller. Backflow suppression means to
The image forming apparatus according to claim 1, further comprising:   The image forming apparatus according to claim 2, wherein the backflow suppressing unit is curved with a surface facing the paper dust removing roller and spaced apart from the surface of the paper dust removing roller.   The image forming apparatus according to claim 1, wherein the paper powder conveying unit and the paper dust removing roller have opposite surfaces rotating in the same direction.

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