JP2006308629A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new image forming apparatus, capable of maintaining proper image quality by efficiently removing paper powder, fiber-like dust, etc., in a plasma charging type electrophotographic recording section. <P>SOLUTION: The image forming apparatus A is equipped with the image recording section 3 which removes foreign matter, such as paper powder sticking on the surface of a photoreceptor drum 5 by a foreign matter removing device 10, after a toner image on the surface of the plasma-charged photoreceptor drum 5 has been transferred to a paper sheet, wherein the foreign matter removing device 10 is equipped with a casing 10a serving as a storage section for the removed foreign matter; a cleaning roller 10b which is arranged in the casing 10 and comes in roll contact with the surface of the photoreceptor drum 5; and a sheet-type slide contact member 10c, which has its base portion fixed to a downstream edge portion of the casing 10a and its free end brought into slide contact with the surface of the photoreceptor drum. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a facsimile machine, a copying machine, or a printer (including these multifunction machines), and more particularly to an image forming apparatus provided with a positively charged electrophotographic recording unit.

As the image forming apparatus as described above, a pair of conveyance rollers (registration roller pair) arranged in the middle of a sheet conveyance path, feeding out sheets (recording sheets) one by one from a sheet feeding unit provided with a sheet cassette or the like. The electrophotographic recording unit is fed to the mating portion of the photosensitive drum and the transfer roller through which the toner image on the surface of the photosensitive drum is transferred to a recording paper, fixed as a permanent image by a fixing device, and then discharged. An image forming apparatus provided with The electrophotographic recording unit includes a cleaning device that removes toner remaining on the surface of the photosensitive drum (image carrier) after the transfer, as disclosed in Patent Document 1. In the image forming apparatus disclosed in Patent Document 1, a member that slides on the image carrier is provided independently of the cleaning device, so that the image carrier is damaged when the cleaning blade is used, residual toner, paper dust, and the like. Measures are also taken to prevent filming caused by the attachment of foreign matter.
JP-A-5-109933

  By the way, recently, a so-called polymerized toner having a nearly spherical shape has been developed by improving the toner, and has been used in the electrophotographic recording system as described above. When such a polymerized toner is employed, the optical resolution of the photosensitive drum is increased, and a single-layer drum can be used. Therefore, the suitability of the positive charging type electrophotographic recording unit is increased. In the case of a positively charged electrophotographic recording unit, the amount of toner remaining on the surface of the photosensitive drum after transfer becomes very small, and a slight amount of remaining toner can be collected by the developing device. It is no longer necessary to provide

  Thus, since the recording paper transported through the paper transport path is easily negatively charged, paper dust or fibrous dust adhering to the recording paper when contacting the positively charged photosensitive drum at the transfer portion, etc. Is strongly attracted to the photosensitive drum electrostatically, and if image recording is continued as it is, it becomes a major cause of deterioration in image recording quality. In particular, fibrous dust tends to adhere to the photosensitive drum and has a great influence on the image quality. When mixed in the developing device, it may stay in the developing device and change the toner composition.

  The present invention has been made in view of the above circumstances, and in a positively charged electrophotographic recording unit, a novel image capable of efficiently removing paper dust and fibrous dust and maintaining image quality at an appropriate level. An object is to provide a forming apparatus.

  In the image forming apparatus according to the first aspect of the present invention, after the toner image on the surface of the photosensitive drum, which is positively charged, is transferred onto the sheet, foreign matter such as paper dust adhering to the surface of the photosensitive drum is removed by the foreign matter removing device. An image forming apparatus including an electrophotographic image recording unit, wherein the foreign matter removing device includes a casing that also serves as a removed foreign matter storage unit, and a cleaning roller that is disposed in the casing and is in contact with the surface of the photosensitive drum. And a sheet-shaped sliding contact member having a base fixed to a downstream side portion of the casing and a free end slidingly contacting the surface of the photosensitive drum.

  In the present invention, as in the second aspect of the present invention, it is desirable that the potential of the cleaning roller is set to be larger on the plus side than the potential at the rolling contact portion of the photosensitive drum with the cleaning roller. Further, as in the invention of claim 3, it is desirable that the sliding contact member is made of a resin film and the free end thereof is elastically contacted in a counter manner with respect to the surface of the photosensitive drum. A non-woven sheet such as felt can be used as the member. In this case, the free end of the casing is elastically slidably contacted against the surface of the photosensitive drum counter-counterly (adapts to the trail side, that is, the rotational direction). It is fixed to the downstream side of the.

  In the image forming apparatus according to the first aspect of the present invention, dust such as paper dust and fibers adhering to the surface of the photosensitive drum at the transfer portion is removed by a cleaning roller that is brought into contact with the surface of the photosensitive drum, and also serves as an accommodating portion. Housed in a casing. The dust that has not been removed by the cleaning roller is removed by the sheet-like sliding contact member located immediately downstream of the cleaning roller and is accommodated in the casing. In particular, since the photosensitive drum is positively charged, it is easy to attract paper dust and fibers, but the removal is made extremely effective by the synergistic action of the cleaning roller and the sheet-like sliding contact member. The adverse effect on quality is reduced.

  Further, as in the second aspect of the present invention, when the potential of the cleaning roller is larger than the potential at the rolling contact portion of the photosensitive drum with the cleaning roller, the dust is larger than the surface of the photosensitive drum. The dust removal effect is further improved by the strong suction to the cleaning roller side and the synergistic action with the sheet-like sliding contact member. Further, if the sheet-like sliding contact member is made of a resin film as in the invention of claim 3, the free end is elastically brought into sliding contact with the surface of the photosensitive drum from its elasticity and waist strength. It is also possible to remove fibrous dust, particularly long fibers, which could not be removed by the cleaning roller.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an example of the image forming apparatus of the present invention, and FIG. 2 is an enlarged view of the main part.

  The image forming apparatus A shown in FIG. 1 is illustrated by taking a printer having an electrophotographic recording unit as an example. However, the image forming apparatus A is not limited to this, and is not limited to this. Needless to say, it may be a so-called multifunction machine or the like. In the figure, the apparatus main body 1 of the image forming apparatus A includes a recording paper (paper) feeding unit 2, an electrophotographic image recording unit 3, and a printed recording paper discharging unit 4 in this order. Layered in the height direction and configured. The recording paper feeding unit 2 includes a detachable paper feeding cassette 2a capable of accumulating and storing a large number of recording papers, a separation paper feeding roller 2b installed at the front end of the paper feeding cassette 2a, and the separation feeding paper. The separation pad 2c is in elastic contact with the peripheral surface of the paper roller 2b.

  The image recording unit 3 is a process in which a positive charging type charger 6, an exposure unit 7 composed of an LED, a developing unit 8, a transfer roller 9, and a foreign matter removing device 10 are arranged in this order around the photosensitive drum 5. And a fixing device 11 on the downstream side thereof. These process units are collectively unitized as process units except for the exposure unit 7 and the transfer roller 9, but the drum unit and the developer unit are separated and can be individually attached to and detached from the apparatus main body 1. It is also possible to configure as described above. In addition to the case where these process units can be inserted and removed in the direction perpendicular to the paper surface in FIG. 1, there are cases where these process units can be taken out above the apparatus main body 1.

  On the downstream side of the fixing device 11, a switching gate 4a, a discharge roller pair 4b, and a discharge tray 4c are connected in series, and the discharge unit 4 is configured by these. A registration roller pair 12 is disposed in the vicinity of the upstream side of the process unit, and the recording paper (paper) separated and fed from the paper feed cassette 2a one by one by the action of the separation paper feed roller 2b and the separation pad 2c. Is registered by the registration roller pair 12 and introduced into a mating portion between the photosensitive drum 5 and the transfer roller 9. While the photosensitive drum 5 rotates in the direction indicated by the arrow in FIG. 1, the surface of the photosensitive drum 5 is uniformly positively charged (about +800 V) by the charger 6, and an optical image based on the image information is formed on the photosensitive drum 5 by the exposure device 7. The surface is irradiated and an electrostatic latent image is formed on the surface of the photosensitive drum 5. This electrostatic latent image is configured such that the potential of the light irradiated portion is lowered (about +100 V) and the potential of other portions (about +800 V) is maintained due to the characteristics of the photoconductor on the surface of the photosensitive drum 5. Is.

  The electrostatic latent image is successively developed by the developing device 8 biased to about +300 V, and reaches a mating portion between the photosensitive drum 5 and the transfer roller 9 as a toner image. During this development, toner is sucked by the photosensitive drum 5 due to a potential difference with the developing unit 8 at a portion where the potential is lowered due to light irradiation, so that a black portion is formed. As a result, a black and white toner image based on the image information is formed. Further, when the toner after transfer, which will be described later, remains in other portions, it is collected by the developing device 8 due to the potential difference between the charging potential and the developing device potential. The registration roller pair 12 is rotationally driven under registration control so that the recording paper is introduced into the mating portion in synchronization with the toner image on the surface of the photosensitive drum 5.

  The transfer roller 9 is biased (-500 V to several kilovolts) and is nip-conveyed with the recording paper while being paired with the photosensitive drum 5 and being rotationally driven in the direction indicated by the arrow (with the photosensitive drum 5 and the width direction). During this time, the toner image on the surface of the photosensitive drum 5 is transferred to the recording paper. The recording paper onto which the toner image has been transferred is introduced into the fixing device 11 and fixed as a permanent image, and then the switching gate 4a is pushed up and discharged onto the discharge tray 4c through the discharge roller pair 4b. This series of recording paper feeds rises substantially vertically (vertically) immediately after feeding from the paper feed cassette 2a, and the discharge roller pair 4b makes a U-turn in a direction of about 180 degrees from the feed direction from the paper feed cassette 2a. The main feeding path P (shown by a one-dot chain line in FIGS. 1 and 2). With such a layout configuration, the entire apparatus can be made compact.

  The image forming apparatus A shown in the figure has a double-sided recording function, and circulates and joins the main feeding path P upstream of the registration roller pair 12 from the mounting position of the switching gate 4a of the main feeding path P. A reverse feeding path P1 is formed. The discharge roller pair 4b can be rotated forward and backward, and the reverse feeding path P1 is provided with a pair of conveying rollers 13 and 14, and when performing double-sided recording, single-sided recording was performed as described above. When the recording paper is conveyed along the main feed path P and the trailing edge of the recording paper reaches the discharge roller pair 4b, the discharge roller pair 4b temporarily stops and nips the trailing edge of the recording paper. Next, the discharge roller pair 4 b is reversed, and the recording paper is conveyed from the rear end thereof by the conveying roller pair 13, 14 through the reverse feeding path P 1, joined to the main feeding path P, and reaches the registration roller pair 12. It is registered by the registration roller pair 12 and is again introduced into the mating portion between the photosensitive drum 5 and the transfer roller 9 to record the back surface thereof. The recording paper recorded on both sides is then discharged onto the discharge tray 4c along the main feeding path P as described above.

  The image forming apparatus A shown in the figure is further provided with a manual sheet feeding function, and a manual tray 15 that can be opened and closed vertically is attached to the side of the apparatus main body 1. When not in use, the manual feed tray 15 is closed as shown by a two-dot chain line in FIG. 1, and can be opened and closed by a handle 15a. A separation feed roller 15b and a separation pad 15c are arranged in a resilient contact state at the front end of the manual feed tray 15, and a manual feed path P2 that joins the main feed path P is further downstream. It is connected continuously.

  When recording an image using the manual feed tray 15, the handle 15 a is opened to open the manual feed tray 15, a recording paper is set thereon, and a manual feed roller 15 b is operated by an appropriate start operation. . The recording paper on the manual feed tray 15 is separated and fed out one by one by the action of the separation paper feed roller 15b and the separation pad 15c, is conveyed through the manual feed path P2, and joins the main feed path P. . Thereafter, the image is registered by the registration roller pair 12 and introduced into the mating portion between the photosensitive drum 5 and the transfer roller 9 for recording. When double-sided recording is performed on the manual recording sheet, the recording sheet is conveyed through the reverse feeding path P1 by the reverse rotation of the discharge roller pair 4b, and the back side recording is performed as described above. The recording paper on which recording has been completed is discharged onto the discharge tray 4c by the discharge roller pair 4b.

  FIG. 2 shows further details of the process part. The developing device 8 includes a stirrer (not shown), a toner supply roller 8b, and a developing roller 8c in a casing 8a that also serves as a toner container. The bias application is substantially performed in the developing roller 8c. A slow power lamp 16 is disposed between the mating portion of the photosensitive drum 5 and the transfer roller 9 and the foreign matter removing device 10, and the slow power lamp 16 provides +100 to 350 V after transfer. The surface potential of the photosensitive drum 5 is adjusted to be a uniform potential of about +100 V before reaching the foreign matter removing apparatus 10.

  The foreign matter removing apparatus 10 includes a casing 10a that also serves as a housing portion for removed foreign matter, a cleaning roller 10b that is disposed in the casing 10a and is brought into contact with the surface of the photosensitive drum 5, and a base portion on a downstream side portion of the casing 10a. And a sheet-like sliding contact member 10c whose free end is in sliding contact with the surface of the photosensitive drum. The cleaning roller 10b is made of sponge-like synthetic rubber or elastic synthetic resin such as silicon, urethane, EPDM, etc., and is disposed so as to roll and rotate with the photosensitive drum 5 (see the arrow in the figure). Bias is applied to a potential higher than the potential of the rolling contact portion, that is, +200 to 600V. The cleaning roller 10b is further provided with a metal roller 10d biased to the plus side so as to make rolling contact (the rotational direction is the direction of the direction), and is made of a sponge, felt, or the like that elastically contacts the metal roller 10d. An elastic member 10e is fixed to the inner surface of the casing 10a.

  A sheet 10f whose tip is lightly in contact with the metal roller 10d is fixed to the inner surface of the casing 10a, and the sheet 10f and the casing 10a form a foreign matter reservoir 10g. Further, a rake sheet 10h is attached in the vicinity of the upstream side of the rolling contact portion of the cleaning roller 10b with the photosensitive drum 5 to prevent the foreign matter from falling off. As shown by a solid line, the sheet-like sliding contact member 10c is made of a resin film, and is attached so that the free end thereof is in elastic sliding contact with the surface of the photosensitive drum 5 in a counter manner, and the sheet-like sliding contact member 10c is fixed. The base, which is the end, is one side on the opening side of the casing 10 a, is parallel to the rotation axis of the photosensitive drum 5, faces the photosensitive drum 5, and is located on the downstream side in the rotation direction of the photosensitive drum 5. It is fixed to the downstream side that is the side. In addition, as shown by a two-dot chain line, it is also possible to use an elastic material such as felt so that the free end is elastically slidably contacted with the surface of the photosensitive drum 5 in an anti-counter manner.

  Next, the function of the foreign matter removing apparatus 10 having the above configuration will be described. On the surface of the photosensitive drum 5 after the transfer, dust such as paper dust and fibers transferred from the recording paper and a small amount of residual toner are attached. At the rolling contact portion between the cleaning roller 10b and the photosensitive drum 5, the surface of the photosensitive drum 5 is made to have a uniform potential of about +100 V by the slow lamp 16 and the residual toner is also positively charged on the surface. Although adhering, the dust is adhering in a negatively charged state. Therefore, at the rolling contact portion, the toner passes while adhering to the photosensitive drum 5 due to a potential difference with the cleaning roller 10b. On the other hand, most of the dust is attracted to and attached to the cleaning roller 10b because the potential of the cleaning roller 10b is larger than the potential of the photosensitive drum 5.

  The dust adhering to the cleaning roller 10b is transferred to the metal roller 10d at the rolling contact portion with the metal roller 10d, and is removed by being wiped off by the elastic member 10e after passing through the portion where the sheet 10f contacts. It is stored in 10 g of the foreign material reservoir. Dust that has not been transferred from the photosensitive drum 5 to the cleaning roller 10b (particularly, dust on long fibers) is removed so as to be scraped off by the sheet-like sliding contact member 10c, and the removed dust is removed from the cleaning roller 10b. Is transferred to the metal roller 10d at the rolling contact portion with the metal roller 10d, and is removed by being wiped by the elastic member 10e in the same manner as described above. Even if the transfer of the dust is not completely performed at the rolling contact portion between the cleaning roller 10b and the metal roller 10d, the dust is eventually removed and accommodated in the foreign matter reservoir 10g while the dust is repeatedly transferred. There is almost no dust adhering to the surface of the photosensitive drum 5 on the downstream side of the apparatus 10, and there is no concern that the quality of image recording will be deteriorated by the dust.

  If the sheet-like sliding contact member 10c is made of a resin film having a waist as described above and is elastically brought into sliding contact with the photosensitive drum 5 in a counter manner, paper dust as well as long fibrous dust can be detected. It can be effectively removed, and a very excellent dust removing function is exhibited by a synergistic effect with the cleaning roller 10b. Since a small amount of toner that remains and adheres to the surface of the photosensitive drum 5 is strongly adsorbed to the photosensitive drum 5, it passes through the elastic sliding contact portion of the sheet-like sliding contact member 10c so as to pass through the charger drum. 6 is charged to a high potential, and is recovered by the potential difference in the developing unit 8 as described above.

  In the above embodiment, an example in which the image forming apparatus A is a single cassette type printer has been described. However, a multi-cassette type printer is not excluded, and an optional cassette is further provided below the recording paper cassette 2a in FIG. Etc. may be stacked.

1 is a longitudinal sectional view illustrating an example of an image forming apparatus of the present invention. It is an enlarged view of the principal part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Image recording part 5 Photosensitive drum 10 Foreign material removal apparatus 10a Casing 10b Cleaning roller 10c Sheet-like slidable contact member A Image forming apparatus

Claims (3)

Image formation with an electrophotographic image recording unit that removes foreign matter such as paper dust adhering to the surface of the photosensitive drum with a foreign matter removing device after transferring the toner image on the surface of the positively charged photosensitive drum to paper A device,
The foreign matter removing apparatus includes a casing that also serves as a housing portion for the removed foreign matter, a cleaning roller that is disposed in the casing and is brought into rolling contact with the surface of the photosensitive drum, and a base that is fixed to a downstream side portion of the casing. An image forming apparatus comprising: a sheet-like sliding contact member that is in sliding contact with the surface of the photosensitive drum. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the potential of the cleaning roller is set to a plus side with respect to a potential at a rolling contact portion of the photosensitive drum with the cleaning roller. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the sliding contact member is made of a resin film, and a free end of the sliding contact member is in elastic contact with the surface of the photosensitive drum in a counter manner.

Images