JP2008242339A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of stably obtaining an excellent image for long time without requiring maintenance. <P>SOLUTION: The image forming apparatus equipped with a corona charger (charging device) 2 for charging a photoreceptor drum (image carrier) 1 is provided with a ventilation means for supplying clean air into the corona charger 2 and an exhaust means for exhausting air around the corona charger 2. Then, a ventilation duct 11 for introducing the clean air supplied from the ventilation means into the corona charger 2 all over the area in a longitudinal direction from the upper part of the corona charger 2 is arranged just above the corona charger 2, and an exhaust duct 14 sucking the air exhausted from the corona charger 2 and scattered toner around a developing device 3 by the exhaust means and exhausting them to the outside of a machine is arranged at a position coming close to the ventilation duct 11 between the corona charger 2 and the developing device 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer provided with a charger for charging an image carrier.

  In an image forming apparatus such as a copying machine or a printer that forms an image by electrophotography, the surface of an image carrier such as a photosensitive drum is uniformly charged by a charger, and image light is applied to the charged image carrier. Irradiation forms an electrostatic latent image on the image carrier. The electrostatic latent image on the image carrier is visualized as a toner image by the developing device, and the toner image is transferred onto the recording material by the transfer device and fixed on the recording material by the fixing device.

  By the way, corona chargers equipped with a charging wire are exposed to discharge products such as ozone generated from the discharge wire along with charging, and scattered toner in process equipment such as a cleaning device and a developing device. Due to the dirt generated by the charging, the charging performance is deteriorated.

Therefore, a blower mechanism (for example, see Patent Document 1) for preventing the charger from being soiled and an automatic cleaning mechanism for removing the soil have been proposed.
Japanese Patent Laid-Open No. 11-143185

  However, removal of the discharge product is not sufficient to prevent the charging performance from deteriorating, and it is necessary to remove the toner cloud floating around the charger at the same time. In order to prevent floating substances from adhering to the periphery of the charger, not only during the image forming operation, but also after the image forming operation is stopped, the air flow is actively blown and exhausted to stop the floating material flow after the operation is stopped. You also need to control.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of stably obtaining a good image over a long period of time without requiring maintenance. .

  In order to achieve the above object, an invention according to claim 1 is an image forming apparatus including a charger for charging an image carrier, and a blowing unit that supplies clean air into the charger, and the charging unit. An exhaust unit for discharging the air around the charger is provided, and a blower duct for introducing clean air supplied from the blower unit into the charger from the upper part to the entire longitudinal direction is disposed immediately above the charger. An exhaust duct that draws air discharged from the charger and toner scattered around the developing device around the developing device and discharges it outside the apparatus is close to the air duct between the charger and the developing device. It is characterized by being arranged at a position.

  According to a second aspect of the present invention, in the first aspect of the invention, the blower unit and the exhaust unit are driven even after the image forming operation is stopped.

  According to the first aspect of the present invention, clean air supplied to the blower duct by the blowing means is introduced into the charger, and discharge products generated by the discharge of the charger are discharged to the outside by the clean air. Therefore, the discharge wire is not contaminated by the discharge product. Also, the air containing the discharge products discharged from the charger and the toner floating around the developing device and the cleaning device are sucked into the exhaust duct from the intake port opened on the lower surface of the exhaust duct by the suction force of the exhaust means. , It is discharged out of the machine through the exhaust duct.

  Therefore, not only discharge products such as ozone generated by charging, but also the toner floating around the developing device and cleaning device are simultaneously discharged and removed, ensuring high charging performance for the corona charger. Thus, a good image can be stably formed over a long period of time without requiring maintenance.

  According to the second aspect of the present invention, the air blower and the exhaust fan are continuously driven not only during the image forming operation but also after the image forming operation is stopped. It is possible to more reliably prevent the deterioration of the charging property associated therewith.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a main part (image forming part) of an image forming apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a photosensitive drum which is an image carrier. A device 2, a developing device 3, a charging roller 4 and a cleaning device 5 are arranged.

  The photosensitive drum 1 is a drum-shaped photosensitive member, and is rotationally driven at a predetermined process speed in a direction indicated by an arrow (counterclockwise) by a driving device (not shown). The corona charger 2 is constructed by extending a discharge wire 7 in the direction perpendicular to the paper surface of FIG. 1 inside a shield plate 6 having a U-shaped cross section. The surface of the photosensitive drum 1 is uniformly charged to a predetermined potential by a charging bias applied to the wire 7.

  The developing device 3 contains toner as a developer and includes a developing roller facing the photosensitive drum 1, and an electrostatic latent image formed on the photosensitive drum 1 as described later is formed by toner. The toner image is developed and visualized as a toner image.

  Further, the cleaning device 5 removes transfer residual toner remaining on the photosensitive drum 1 after the transfer of the toner image to clean the surface of the photosensitive drum 1, and is a cleaning blade that slides on the surface of the photosensitive drum 1. 9 is provided.

  Next, the gist of the present invention will be described with reference to FIGS.

  2 is a cross-sectional view showing a blower / exhaust structure around a charger of the image forming apparatus according to the present invention, FIG. 3 is a perspective view thereof, and FIG. 4 is a perspective view of the entire image forming unit including a blower / exhaust unit. 5 is a perspective view of the blower / exhaust structure, and FIG. 6 is a plan view of the blower / exhaust structure.

  As shown in FIGS. 2 and 3, the shield plate 6 of the corona charger 2 extends to the photosensitive drum 1 along the axial direction (perpendicular to the plane of FIG. 2), and at the center of the upper surface in the width direction. A slit-shaped opening 6a is formed along the longitudinal direction. A grid 10 is disposed on the lower surface of the shield plate 6 facing the photosensitive drum 1, and slit-like openings 6 b are formed along the longitudinal direction between the grid 10 and the shield plate 6 on both sides in the width direction. Is formed.

  Thus, the air duct 11 is disposed along the corona charger 2 immediately above the corona charger 2, and the discharge port 11 a on the lower surface is formed on the upper surface of the shield plate 6 of the corona charger 2. The opening 6a is opened over the entire area. As shown in FIGS. 4 to 6, a blower fan 12, which is a blowing means, is connected to one end of the blower duct 11 (one end on the near side in FIGS. 4 to 6) via a blower duct 13.

  In addition, as shown in FIG. 2, in the circumferential direction on the outer peripheral side of the photosensitive drum 1, a space between the developing device 3 and the corona charger 2 and in the vicinity of the air duct 11 is located on the lower surface. An exhaust duct 14 having a U-shaped cross section that opens as an air inlet 14 a is arranged in parallel with the air duct 11. As shown in FIGS. 4 and 5, an exhaust fan 15, which is an exhaust means, is connected to one end of the exhaust duct 14 (one end on the back side in FIGS. 4 and 5) via an exhaust duct 16.

  In the image forming apparatus configured as described above, when the image forming operation is started, the photosensitive drum 1 is rotated at a predetermined process speed in the direction of the arrow in FIG. As described above, the surface of the corona charger 2 is uniformly charged to a predetermined potential. When image light is irradiated onto the photosensitive drum 1 whose surface is uniformly charged in this way, an electrostatic latent image corresponding to the image is formed on the photosensitive drum 1, and this electrostatic latent image is developed. The apparatus 3 visualizes the toner image.

  On the other hand, a recording material P such as paper is fed from a paper feeding device (not shown) to a transfer nip portion formed between the photosensitive drum 1 and the transfer roller 4 at a predetermined timing, and a transfer bias applied to the transfer roller 4. As a result, the toner image on the photosensitive drum 1 is transferred onto the recording material P. At this time, the transfer residual toner which is not transferred onto the recording material P and remains on the photosensitive drum 1 is removed by the cleaning device 5 as described above, and the photosensitive drum 1 whose surface is cleaned is prepared for the next image formation. It is done.

  Thus, the recording material P onto which the toner image has been transferred as described above is conveyed to a fixing device (not shown), and the toner image is heated and pressurized in the process of passing through the fixing device, thereby The toner image is fixed on the recording material P as a permanent image. The recording material P on which the toner image has been fixed in this manner is discharged out of the apparatus and stacked on a discharge tray (not shown).

  The above is a series of image forming operations. Even during the image forming operation and after the image forming operation is stopped, the blower fan 12 and the exhaust fan 15 shown in FIGS. 12 is introduced into the air duct 11 through the air duct 13. Then, the clean air introduced into the air duct 11 flows in the air duct 11 along the longitudinal direction of the corona charger 2, and as shown by arrows in FIG. The corona charger 2 is introduced into the corona charger 2 through the opening 6a on the upper surface of the corona charger 2 from the opening 11a.

  The clean air introduced into the corona charger 2 as described above is discharged to the outside from the lower surface opening 6 b of the corona charger 2 together with discharge products such as ozone generated by the discharge by the discharge wire 7. For this reason, the discharge product generated by the discharge of the corona charger 2 is discharged out of the corona charger 2 by air, the discharge wire 7 is not contaminated by the discharge product, and the corona charger 2 has high charging performance. Secured.

  Also, the air discharged together with the discharge products outside the corona charger 2 and the toner floating around the developing device 3 and the cleaning device 5 are exhausted by the suction force of the exhaust fan 15 as indicated by arrows in FIG. The air is sucked into the exhaust duct 14 from the intake port 14a opened on the lower surface of the duct 14, flows in the exhaust duct 14 along the longitudinal direction, and is finally discharged to the outside through the exhaust duct 16.

  As described above, in the present embodiment, clean air supplied to the blower duct 11 by the blower fan 12 is introduced into the corona charger 2, and the discharge product generated by the discharge of the corona charger 2 is clean. Therefore, the discharge wire 7 is not contaminated by the discharge product.

  In addition, air containing discharge products discharged from the corona charger 2 and toner floating around the developing device 3 and the cleaning device 5 are sucked into the lower surface of the exhaust duct 14 by the suction force of the exhaust fan 15. The air is sucked into the exhaust duct 14 and discharged to the outside through the exhaust duct 16.

  Therefore, according to the present embodiment, not only discharge products such as ozone generated by charging but also the toner floating around the developing device 3 and the cleaning device 5 are simultaneously discharged out of the apparatus and removed. Further, contamination of the corona charger 2 is prevented, high charging performance is ensured, and a good image can be stably formed over a long time without requiring maintenance. In particular, in the present embodiment, the air blower 12 and the exhaust fan 15 are continuously driven not only during the image forming operation but also after the image forming operation is stopped. In addition, it is possible to more reliably prevent the deterioration of chargeability associated therewith.

  Further, in the present embodiment, the exhaust duct 14 is arranged close to the side of the blower duct 11 so that the intake port 14a of the exhaust duct 14 is as far away as possible from the surface of the photosensitive drum 1. Therefore, the corona charger It is possible to prevent paper dust and the like from adhering to the grid 10 of No. 2.

  In an image forming apparatus adopting a configuration in which the image forming unit including the photosensitive drum and the charger can be pulled out from the front side, the air duct and the exhaust duct are not pulled out at the same time and are left on the main body side in consideration of maintainability. Is preferred.

1 is a cross-sectional view of a main part (image forming part) of an image forming apparatus according to the present invention. FIG. 3 is a cross-sectional view showing a blower / exhaust structure around a charger of the image forming apparatus according to the present invention. 1 is a perspective view of an entire image forming unit including a blower / exhaust unit of an image forming apparatus according to the present invention. 1 is a perspective view of an entire image forming unit including a blower / exhaust unit of an image forming apparatus according to the present invention. 1 is a perspective view of a blower / exhaust structure of an image forming apparatus according to the present invention. 1 is a plan view of a blower / exhaust structure of an image forming apparatus according to the present invention.

Explanation of symbols

1 Photosensitive drum (image carrier)
2 Corona charger (charger)
DESCRIPTION OF SYMBOLS 3 Developing device 4 Transfer roller 5 Cleaning device 6 Shield plate 6a Shield plate upper surface opening 6b Shield plate lower surface opening 7 Discharge wire 8 Developing roller 9 Cleaning blade 10 Grid 11 Blower duct 11a Blower duct outlet 12 Blower fan ( Air blowing means)
13 Blower Duct 14 Exhaust Duct 14a Exhaust Duct Inlet 15 Exhaust Fan (Exhaust Means)
16 Exhaust duct P Recording material

Claims (2)

In an image forming apparatus provided with a charger for charging an image carrier,
A blower means for supplying clean air into the charger and an exhaust means for discharging the air around the charger are provided, and the clean air supplied from the blower is longitudinally inserted into the charger from above. An air exhaust duct that is arranged over the entire direction is disposed immediately above the charger, and the air discharged from the charger and the toner scattered around the developing device are sucked out by the exhaust means and discharged outside the apparatus. Is disposed at a position close to the air duct between the charger and the developing device.   2. The image forming apparatus according to claim 1, wherein the air blowing unit and the exhaust unit are driven even after the image forming operation is stopped.

Images