Patent Publication Number: US-6701122-B2

Title: Cleaning device and image forming apparatus having it

Description:
FIELD OF THE INVENTION 
     This invention relates to a cleaning device for removing an untransferred toner remaining on the circumferential surface of a photoconductor drum, and more specifically, to a cleaning device disposed above the photoconductor drum, and an image forming apparatus equipped with the cleaning device. 
     DESCRIPTION OF THE PRIOR ART 
     In recent years, there have been increases in electrostatic copiers of an in-body paper delivery type in which a paper stack space is provided in a region between image forming means, including a photoconductor drum, and document exposure/image reading means disposed above the image forming means in the body of an image forming apparatus to achieve compactness of the entire apparatus. In such a copier, paper is transported vertically upwardly from a paper feed cassette or a manual paper feed tray disposed below the image forming means. While the paper transported vertically upwardly is passing through a transfer zone disposed beside the photoconductor drum, a toner is transferred to the paper by transfer means. The paper having the toner transferred thereto is transported, unchanged, vertically upwardly, and then passed beside a fixing device. During this passage, the toner transferred to the paper is fixed onto the paper. The paper bearing the fixed toner is transported vertically upwardly, then changed in the direction of transport, and transported in a horizontal direction. Finally, the paper is delivered to a paper receiving tray in the paper stack space. The untransferred toner, which has not been transferred onto the paper, but has remained on the circumferential surface of the photoconductor drum, is removed by a cleaning device provided downstream from the transfer zone in the direction of rotation of the photoconductor drum. In such a copier of the in-body paper delivery type, the paper is transported vertically upwardly beside the photoconductor drum. Thus, there is no choice but to provide the cleaning device above the photoconductor drum. As a result, the cleaning device is configured to have a lower end portion downwardly opening toward the circumferential surface of the photoconductor drum. 
     Of the copiers of the in-body paper delivery type, those operating at a low speed have been predominant conventionally, but have recently been replaced by high speed ones gradually. With this technical background, the copiers in the above-mentioned configuration are increasing the use of a low temperature fixing toner, an a-Si(amorphous silicon)-based photoconductor drum, or a high sensitivity OPC (Organic Photoconductor) photoconductor drum. 
     When the toner remaining on the circumferential surface of the photoconductor drum is removed using a cleaning blade, additives detached from the toner may deposit on the circumferential surface of the photoconductor drum, and may be unremovable by cleaning. If the additives remain on the circumferential surface of the photoconductor drum, the remaining additives form cores, around which the poorly cleanable toner grows, forming masses. Every time the resulting masses slip beside the cleaning blade, they fuse, leaving streaky toner deposits on the circumferential surface of the photoconductor drum. Since a fresh toner is developed on the toner deposits, copy smudges resembling black spots corresponding to the toner deposits appear on the surface of the paper which is a copy. Particularly when the low temperature fixing toner is used, this tendency is marked. With the speeding of the in-body paper delivery type copier, a demand is becoming intense for a solution to this problem. Furthermore, when a magnetic toner is used, the following facts are presented: First, a magnetic powder contained in the magnetic toner, such as magnetite, becomes a causative substance, like the aforementioned detached additives, for the toner deposits on the circumferential surface of the photoconductor drum. Secondly, if a high copying speed is intended, a binder resin needs to have the property of fixing at an even lower temperature, in order to obtain fixing performance comparable to that of a nonmagnetic toner with the use of the magnetic toner. For these reasons, black spot-like copy smudges may occur noticeably. Even in light of the difference in weight between the magnetic toner and the nonmagnetic toner, if the copying speed of the in-body paper delivery type copier is increased, black spot-like smudges of the copy due to the deposition of the toner is even more marked, posing a problem to be solved. 
     Furthermore, the photoconductor drum itself poses the following problem: When an a-Si-based photoconductor drum is used, products of electric discharge, such as NO x  and SO x , are generated by a main charger, a transfer charger, and a static eliminator disposed around the photoconductor drum. When these discharge products are exposed to a high humidity environment while depositing on the circumferential surface of the photoconductor drum, they adsorb moisture in the air to disturb an electrostatic latent image on the circumferential surface of the photoconductor drum, thereby causing image distortion. In addition, ozone which develops from the chargers and the static eliminator oxidizes and deteriorates the circumferential surface of the photoconductor drum, causing a tendency toward aggravation of image distortion. If a photoconductor drum other than the a-Si-based photoconductor drum, for example, the OPC photoconductor drum, is used, on the other hand, the toner undergoes filming on the circumferential surface of the photoconductor drum. As a result, photosensitivity and chargeability decline, so that fog in non-image areas or a decrease in image density tends to occur. Filming of the toner refers to the phenomenon that during repeated image formation and cleaning for long periods of time, the toner particles pressed against, slid over and rubbed against the circumferential surface of the photoconductor drum by the cleaning blade are deformed plastically and fused in a film form onto the circumferential surface. 
     To deal with the foregoing problems, it is necessary to polish the circumferential surface of the photoconductor drum aggressively, and always maintain the circumferential surface of the photoconductor drum in a clean state. For this purpose, a cleaning roller composed of an elastic material such as urethane rubber is provided upstream from the cleaning blade. This cleaning roller is driven so as to be rotationally moved in the same direction as the photoconductor drum at a peripheral speed higher than that of the photoconductor drum at the site of its pressurized contact with the photoconductor drum. Alternatively, the cleaning roller is rotated in a manner following the photoconductor drum. By so doing, the cleaning roller is slid over and rubbed against the circumferential surface of the photoconductor drum to polish it. More concretely, the cleaning roller shows its own action of cleaning, and in addition, polishes the circumferential surface of the photoconductor drum by sliding on and rubbing against it via the toner and the toner additives remaining on the circumferential surface of the photoconductor drum, thereby keeping the circumferential surface of the photoconductor drum always clean. Consequently, image distortion, toner filming, or toner deposition on the circumferential surface of the photoconductor drum is prevented. 
     As described above, it is desirable in the in-body paper delivery type copier to provide the cleaning roller in the cleaning device. However, the provision of the cleaning roller in addition to the cleaning blade and the toner outletting spiral means requires a considerable proportion of the space around the photoconductor drum, inducing upsizing of the entire copier. An alternative measure would be to thrust the cleaning blade in the axial direction of the photoconductor drum, thereby minimizing the slipping escape of the deposited toner from the cleaning blade. Even if this measure is taken, however, image distortion and toner filming cannot be prevented effectively, and seal between the cleaning blade and the circumferential surface of the photoconductor drum is decreased, whereupon the toner falls toward the photoconductor drum, causing the risks of copy smudges and dirt inside the apparatus. Besides, because of the thrust of the cleaning blade, the edge face of the cleaning blade is liable to damage, disadvantaging the long life of the apparatus. 
     A further problem with the prior art exists. That is, when an ordinary cleaning device is disposed, unchanged, above the photoconductor drum, the toner outletting spiral means is provided upstream from the cleaning blade in the direction of rotation of the photoconductor drum. Thus, the toner recovered is rendered stagnant above the cleaning blade by the transport action of the photoconductor drum itself, whereby the toner transport ability of the toner outletting spiral means fails to work effectively. As a result, toner agglomeration, toner blocking or the like occurs, so that the action of outletting the recovered toner is itself insufficient. In the worst case, there may be a serious trouble, such as the toner outletting spiral means becoming locked. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a novel cleaning device, which accommodates a cleaning blade, a cleaning roller and toner outletting spiral means compactly and which can downsize the entire structure, and more specifically, a novel cleaning device disposed above a photoconductor drum for removing an untransferred toner remaining on the circumferential surface of the photoconductor drum; and a novel image forming apparatus equipped with the cleaning device. 
     Another object of the present invention is to provide a novel cleaning device which prevents the occurrence of toner agglomeration or toner blocking until the recovered toner is let out, and which enables the recovered toner to be transported and let out smoothly and promptly, and more specifically, a novel cleaning device disposed above the photoconductor drum for removing an untransferred toner remaining on the circumferential surface of the photoconductor drum; and a novel image forming apparatus equipped with the cleaning device. 
     Yet another object of the present invention is to provide a novel cleaning device which enables the recovered toner to be promptly transported toward the outside and let out without being leaked to the outside, and more specifically, a novel cleaning device disposed above the photoconductor drum for removing an untransferred toner remaining on the circumferential surface of the photoconductor drum; and a novel image forming apparatus equipped with the cleaning device. 
     A further object of the present invention is to provide a novel image forming apparatus of an in-body paper delivery type which ensures satisfactory image formation and which permits a high copying speed. 
     A still further object of the present invention is to provide a novel image forming apparatus of an in-body paper delivery type which prevents image distortion, toner filming and toner deposition occurring on the circumferential surface of the photoconductor drum, and which enables a maintenance cycle to be extended. 
     According to an aspect of the present invention, there is provided a cleaning device comprising: 
     a housing disposed above a photoconductor drum and having an opening portion open downward toward a circumferential surface of the photoconductor drum; 
     a cleaning blade disposed in the housing so as to be located in the opening portion downstream in a direction of rotation of the photoconductor drum; and 
     a cleaning roller disposed in the housing so as to be located in the opening portion upstream from the cleaning blade in the direction of rotation of the photoconductor drum, and wherein, in the housing, 
     toner outletting spiral means for letting out a toner recovered into the housing is disposed above the cleaning blade; 
     a partition wall is disposed between the cleaning blade and the toner outletting spiral means; and 
     a toner movement space for moving the toner recovered into the housing is formed between a front end of the partition wall and a circumferential surface of the cleaning roller. 
     Preferably, when a rotation region of the toner outletting spiral means is viewed in a vertical direction, the partition wall extends out from a downstream end of the rotation region toward an upstream end of the rotation region in the direction of rotation of the photoconductor drum; and when the rotation region is viewed in the vertical direction, an effective length of shielding of the rotation region by the partition wall is 30% or more of a diameter of the rotation region. 
     Preferably, the front end of the partition wall is disposed nearly vertically below a center of rotation of the toner outletting spiral means. 
     Preferably, the horizontal distance at which the front end of the partition wall and the circumferential surface of the cleaning roller maximally approach each other is 2 mm or more. 
     Preferably, the circumferential surface of the cleaning roller rotationally moves in the same direction as the circumferential surface of the photoconductor drum at a site of pressurized contact between the circumferential surface of the cleaning roller and the circumferential surface of the photoconductor drum; a scraper is disposed within the housing; and a front end portion of the scraper is brought into pressurized contact with the circumferential surface of the cleaning roller at a position downstream from the site of pressurized contact between the circumferential surface of the cleaning roller and the circumferential surface of the photoconductor drum in a direction of rotation of the cleaning roller, with a front end of the scraper being directed in a direction opposite to the direction of rotation of the cleaning roller. 
     Preferably, the scraper is disposed so as to be capable of scraping off the toner deposited on the circumferential surface of the cleaning roller either to a gap between the cleaning roller and the toner outletting spiral means, or toward a rotation region of the toner outletting spiral means. 
     Preferably, the distance at which the circumferential surface of the cleaning roller and a rotation region of the toner outletting spiral means maximally approach each other is 3 mm or less. 
     Preferably, the cleaning roller functions as a polishing roller, because the circumferential surface of the cleaning roller makes pressurized contact with the circumferential surface of the photoconductor drum via the toner. 
     According to another aspect of the present invention, there is provided a cleaning device comprising: 
     a housing disposed above a photoconductor drum and having an opening portion open downward toward a circumferential surface of the photoconductor drum; 
     a cleaning blade disposed in the housing so as to be located in the opening portion downstream in a direction of rotation of the photoconductor drum; and 
     a cleaning roller disposed in the housing so as to be located in the opening portion upstream from the cleaning blade in the direction of rotation of the photoconductor drum, and wherein 
     toner outletting spiral means for letting out a toner recovered into the housing is disposed above the cleaning blade in the housing; 
     a scraper is disposed within the housing; 
     a circumferential surface of the cleaning roller rotationally moves in the same direction as the circumferential surface of the photoconductor drum at a site of pressurized contact between the circumferential surface of the cleaning roller and the circumferential surface of the photoconductor drum; 
     a front end portion of the scraper is brought into pressurized contact with the circumferential surface of the cleaning roller at a position downstream from the site of pressurized contact between the circumferential surface of the cleaning roller and the circumferential surface of the photoconductor drum in a direction of rotation of the cleaning roller, with a front end of the scraper being directed in a direction opposite to the direction of rotation of the cleaning roller; and 
     the scraper is disposed so as to be capable of scraping off the toner deposited on the circumferential surface of the cleaning roller either to a gap between the cleaning roller and the toner outletting spiral means, or toward a rotation region of the toner outletting spiral means. 
     Preferably, in the housing, a partition wall is disposed between the cleaning blade and the toner outletting spiral means; and a toner movement space for moving the toner recovered into the housing is formed between a front end of the partition wall and the circumferential surface of the cleaning roller. 
     Preferably, the cleaning roller functions as a polishing roller, because the circumferential surface of the cleaning roller makes pressurized contact with the circumferential surface of the photoconductor drum via the toner. 
     According to still another aspect of the present invention, there is provided an image forming apparatus comprising: 
     a photoconductor drum; and 
     a cleaning device for removing a toner remaining on a circumferential surface of the photoconductor drum, 
     the cleaning device comprising: 
     a housing disposed above a photoconductor drum and having an opening portion open downward toward the circumferential surface of the photoconductor drum; 
     a cleaning blade disposed in the housing so as to be located in the opening portion downstream in a direction of rotation of the photoconductor drum; and 
     a cleaning roller disposed in the housing so as to be located in the opening portion upstream from the cleaning blade in the direction of rotation of the photoconductor drum, and wherein, in the housing, 
     toner outletting spiral means for letting out the toner recovered into the housing is disposed above the cleaning blade; 
     a partition wall is disposed between the cleaning blade and the toner outletting spiral means; and 
     a toner movement space for moving the toner recovered into the housing is formed between a front end of the partition wall and a circumferential surface of the cleaning roller. 
     Preferably, when a rotation region of the toner outletting spiral means is viewed in a vertical direction, the partition wall extends out from a downstream end of the rotation region toward an upstream end of the rotation region in the direction of rotation of the photoconductor drum; and when the rotation region is viewed in the vertical direction, an effective length of shielding of the rotation region by the partition wall is 30% or more of a diameter of the rotation region. 
     Preferably, the front end of the partition wall is disposed nearly vertically below a center of rotation of the toner outletting spiral means. 
     Preferably, the horizontal distance at which the front end of the partition wall and the circumferential surface of the cleaning roller maximally approach each other is 2 mm or more. 
     Preferably, the circumferential surface of the cleaning roller rotationally moves in the same direction as the circumferential surface of the photoconductor drum at a site of pressurized contact between the circumferential surface of the cleaning roller and the circumferential surface of the photoconductor drum; a scraper is disposed within the housing; and a front end portion of the scraper is brought into pressurized contact with the circumferential surface of the cleaning roller at a position downstream from the site of pressurized contact between the circumferential surface of the cleaning roller and the circumferential surface of the photoconductor drum in a direction of rotation of the cleaning roller, with a front end of the scraper being directed in a direction opposite to the direction of rotation of the cleaning roller. 
     Preferably, the scraper is disposed so as to be capable of scraping off the toner deposited on the circumferential surface of the cleaning roller either to a gap between the cleaning roller and the toner outletting spiral means, or toward a rotation region of the toner outletting spiral means. 
     Preferably, the distance at which the circumferential surface of the cleaning roller and a rotation region of the toner outletting spiral means maximally approach each other is 3 mm or less. 
     Preferably, the cleaning roller functions as a polishing roller, because the circumferential surface of the cleaning roller makes pressurized contact with the circumferential surface of the photoconductor drum via the toner. 
     Preferably, the image forming apparatus comprises an image forming apparatus body; image forming means disposed in the body and including the photoconductor drum and the cleaning device; document exposure/image reading means disposed within an upper end portion of the body and above the image forming means; a paper stack space portion disposed in a region between the image forming means and the document exposure/image reading means in the body; and a paper transport passage extending in a vertical direction beside the photoconductor drum and adapted to guide fed paper to the paper stack space portion. 
     Preferably, the photoconductor drum comprises an a-Si-based photoconductor drum, and the peripheral speed of the cleaning roller is greater than the peripheral speed of the photoconductor drum. 
     Preferably, the toner comprises a magnetic toner. 
     According to a further aspect of the present invention, there is provided an image forming apparatus comprising: 
     a photoconductor drum; and 
     a cleaning device for removing a toner remaining on a circumferential surface of the photoconductor drum, 
     the cleaning device comprising: 
     a housing disposed above the photoconductor drum and having an opening portion open downward toward the circumferential surface of the photoconductor drum; 
     a cleaning blade disposed in the housing so as to be located in the opening portion downstream in a direction of rotation of the photoconductor drum; and 
     a cleaning roller disposed in the housing so as to be located in the opening portion upstream from the cleaning blade in the direction of rotation of the photoconductor drum, and wherein 
     toner outletting spiral means for letting out the toner recovered into the housing is disposed above the cleaning blade in the housing; 
     a scraper is disposed within the housing; 
     a circumferential surface of the cleaning roller rotationally moves in the same direction as the circumferential surface of the photoconductor drum at a site of pressurized contact between the circumferential surface of the cleaning roller and the circumferential surface of the photoconductor drum; 
     a front end portion of the scraper is brought into pressurized contact with the circumferential surface of the cleaning roller at a position downstream from the site of pressurized contact between the circumferential surface of the cleaning roller and the circumferential surface of the photoconductor drum in a direction of rotation of the cleaning roller, with a front end of the scraper being directed in a direction opposite to the direction of rotation of the cleaning roller; and 
     the scraper is disposed so as to be capable of scraping off the toner deposited on the circumferential surface of the cleaning roller either to a gap between the cleaning roller and the toner outletting spiral means, or toward a rotation region of the toner outletting spiral means. 
     Preferably, in the housing, a partition wall is disposed between the cleaning blade and the toner outletting spiral means; and a toner movement space for moving the toner recovered into the housing is formed between a front end of the partition wall and the circumferential surface of the cleaning roller. 
     Preferably, the cleaning roller functions as a polishing roller, because the circumferential surface of the cleaning roller makes pressurized contact with the circumferential surface of the photoconductor drum via the toner. 
     Preferably, the image forming apparatus comprises: an image forming apparatus body; image forming means disposed in the body and including the photoconductor drum and the cleaning device; document exposure/image reading means disposed within an upper end portion of the body and above the image forming means; a paper stack space portion disposed in a region between the image forming means and the document exposure/image reading means in the body; and a paper transport passage extending in a vertical direction beside the photoconductor drum and adapted to guide fed paper to the paper stack space portion. 
     Preferably, the photoconductor drum comprises an a-Si-based photoconductor drum, and a peripheral speed of the cleaning roller is greater than a peripheral speed of the photoconductor drum. 
     Preferably, the toner comprises a magnetic toner. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing an external outline configuration of an electrostatic copier of an in-body paper delivery type equipped with an embodiment of a cleaning device according to the present invention; 
     FIG. 2 is a front view of the copier shown in FIG. 1 as a sectional schematic view showing an internal construction; 
     FIG. 3 is a schematic view of the copier shown in FIG. 1, as viewed from the right in FIG. 1, illustrating the open and closed states of a document feeder; 
     FIG. 4 is a sectional schematic view showing an internal construction of the cleaning device provided in the copier shown in FIG. 1; and 
     FIG. 5 is a sectional schematic view for illustrating the positional relationship among constituent elements in the cleaning device shown in FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of a cleaning device constructed according to the present invention, and embodiments of an electrostatic copier, as an image forming apparatus, equipped with the cleaning device, and more specifically, an electrostatic copier of the in-body paper delivery type, will now be described in detail with reference to the accompanying drawings. 
     With reference to FIGS. 1 and 2, a copier  100  has a copier body  102  having a nearly rectangular parallelopipedal contour as a whole. The copier body  102  has a lower body  102 L, an upper body  102 U disposed above the lower body  102 L and at a distance therefrom, and a one-side portion connecting body  102 S and a rear end portion connecting body  102 B which connect the lower body  102 L and the upper body  102 U integrally to each other. When the copier body  102  is viewed from front (viewed in the direction of an arrow A in FIG. 1; viewed from the sheet face of FIG.  2 ), the one-side portion connecting body  102 S extends vertically between one-side portions of the lower body  102 L and the upper body  102 U (between their left side portions in FIGS. 1 and 2) to connect these one-side portions, while the rear end portion connecting body  102 B extends vertically between rear end portions of the lower body  102 L and the upper body  102 U to connect these rear end portions. The upper body  102 U is present in an upper end portion of the copier body  102 . In a space between the lower body  102 L and the upper body  102 U in the copier body  102 , a paper stack space portion  104  is formed which is open at the front surface and the other side surface of the copier body  102  when the copier body  102  is viewed from front. The bottom surface of the paper stack space portion  104  comprises a horizontal upper surface of the lower body  102 L, while the top surface of the paper stack space portion  104  comprises a horizontal lower surface of the upper body  102 U. In the paper stack space portion  104 , an upper paper receiving tray  104   a  and a lower paper receiving tray  104   b  are horizontally disposed with spacing in an up-down direction. In the one-side portion connecting body  102 S, an upper paper outlet opening  102 S a  and a lower paper outlet opening  102 S b  are disposed with spacing in the up-down direction. Paper transported through a paper transport passage  32  (to be described later on) is let out onto the upper paper receiving tray  104   a  or the lower paper receiving tray  104   b  through the upper paper outlet opening  102 S a  or the lower paper outlet opening  102 S b , respectively. 
     An operating panel  105  is disposed in a front region, opposed to an operator, of the upper surface of the upper body  102 U, and a document bearing board  106  comprising a transparent glass plate is horizontally disposed in the other wide region of the upper surface of the upper body  102 U. A document feeder  10  for transporting a document to an image reading position R so that the image of the document may be read is pivotally disposed on the upper body  102 U. The document feeder  10  includes a document feeder body  10 A, a document cover  10 B, a document feeding tray  10 C, and a document receiving tray  10 D. The document cover  10 B is formed integrally with the document feeder body  10 A, and extends rightwardly horizontally in FIG. 2 from a lower end portion of the document feeder body  10 A. The lower surface of the document cover  10 B and the lower surface of the document feeder body  10 A are existent on the same plane. The document receiving tray  10 D is formed integrally with the upper surface of the document cover  10 B. The document feeding tray  10 C is disposed in the document feeder body  10 A so as to extend obliquely upwardly to the right in FIG. 2 from an upper end portion of the document feeder body  10 A. As shown in FIG. 3, the document feeder  10  is supported on the upper body  102 U so as to be pivotable via hinge means  108  disposed on a rear side of the upper body  102 U. The document feeder  10  is pivotable between a closed position indicated by solid lines in FIG.  3  and an open position indicated by two-dot chain lines in FIG.  3 . When located at the closed position, the document feeder  10  covers the entire surface of the document bearing board  106  from above. When located at the open position, the document feeder  10  makes the entire surface of the document bearing board  106  open upwardly. 
     The document feeder  10 , when located at the closed position, will be described further. A document transport passage  11  is disposed inside the document feeder body  10 A. The document transport passage  11  extends obliquely downwardly to the left from a right-hand upper end portion of the document feeder body  10 A in FIG. 2, curves and reverses toward the image reading position R disposed in a left end portion of the document bearing board  106 , and then extends obliquely upwardly to the right toward a right-hand lower end portion of the document feeder body  10 A in FIG.  2 . The document feeding tray  10 C is disposed on an extension of the upstream end of the document transport passage  11 , and the document receiving tray  10 D extends on an extension of the downstream end of the document transport passage  11 . In the document feeder body  10 A, a pickup roller  12 , a transport roller pair  13 , a register roller pair  14 , and an outlet roller pair  15  are provided in this order along the document transport passage  11  from an upstream region toward a downstream region in the direction of document transport. The transport roller pair  13  is composed of a drive roller  13   a  and a separation roller  13   b . The separation roller  13   b  rotationally moves in a direction opposite to the drive roller  13   a  at the site of nip only when the rotation load falls short of a predetermined torque. When the rotation load exceeds the predetermined torque, the separation roller  13   b  rotates following the drive roller  13   a . A spring member  16   a  and a set document pressing member  16   b  are disposed in an upstream end region of the document transport passage  11  and nearly below the pickup roller  12 . The set document pressing member  16   b  is urged upward toward the pickup roller  12  by the spring member  16   a.    
     The image reading position R is provided between the register roller pair  14  and the outlet roller pair  15  in the document transport passage  11 . At the image reading position R, the document transport passage  11  is formed by cooperation between the document feeder body  10 A and the document bearing board  106 . A white reference plate  17  for shading correction, and document hold-down means  17   a  are disposed in the document feeder body  10 A. The white reference plate  17  is opposed to the document bearing board  106  from above at the image reading position R. The document hold-down means  17   a  is disposed on the upper side of the white reference plate  17  to press the white reference plate  17  against the upper surface of the document bearing board  106 . 
     A plurality of sensors are disposed in the document feeder  10 . That is, a document setting detection sensor S 1  is disposed in a middle portion of the document feeding tray  10 C, a feeding sensor S 2  is disposed downstream from the transport roller pair  13 , and a document outletting sensor S 3  is disposed downstream from the outlet roller pair  15 . 
     In the upper body  102 U, document exposure/image reading means  20  is disposed for exposing the document, which is transported through the document transport passage  11  by the document feeder  10 , to light at the image reading position R to read the image of the document. As shown in FIG. 2, the document exposure/image reading means  20  includes an exposure lamp  21 , a reflecting plate  22  for reflecting light from the exposure lamp  21 , a first mirror  23 , a second mirror  24  and a third mirror  25  for receiving reflected light from the document passing the image reading position R and reflecting this light, a condenser lens  26 , and an image sensor, e.g. a line type CCD,  27 . The exposure lamp  21 , the reflecting plate  22 , and the first mirror  23  are loaded on a first carriage Cl which is movable in a right-left direction in FIG.  2 . The second mirror  24  and the third mirror  25  are loaded on a second carriage C 2  which is movable in the right-left direction in FIG.  2 . 
     The copier  100  adopts two methods for reading the image of the document, a so-called sheet through method and a document fixing method. According to the sheet through method, with the document feeder  10  being located at the closed position, the image of the document passing the image reading position R is relatively scanned and read by the document exposure/image reading means  20  while the first carriage C 1  and the second carriage C 2  are being kept at a predetermined image reading stationary position (the position shown in FIG.  2 ). When the first carriage C 1  and the second carriage C 2  are at a standstill at the image reading stationary position shown in FIG. 2, the exposure lamp  21 , the reflecting plate  22  and the first mirror  23  loaded on the first carriage C 1  are positioned in a region nearly directly below the image reading position R. According to the document fixing method, on the other hand, with the document being placed on the upper surface of the document bearing board  106  and the document feeder  10  being located at the closed position, the first carriage C 1  and the second carriage C 2  are each moved, whereby the image of the document stopped on the upper surface of the document bearing board  106  is scanned and read by the document exposure/image reading means  20 . Both types of reading the image of the document are available for the copier  100 . 
     Operations of the document feeder  10  and the document exposure/image reading means  20  will be described in accordance with the above-mentioned sheet through method. With reference to FIG. 2, with the document feeder  10  being located at the closed position, n documents set on the document feeding tray  10 C, with their image surfaces facing upward, are pressed against the pickup roller  12  at a predetermined pressure by the set document pressing member  16   b  urged upward by the spring member  16   a . When a copy start button (not shown) disposed on the operating panel  105  is depressed into the ON-state, the pickup roller  12  and the transport roller pair  13  are rotationally driven by primary feeding drive means (not shown). The documents set on the document feeding tray  10 C are sent, usually in plural numbers, starting with the upwardly facing side of the documents, to the transport roller pair  13  by the pickup roller  12 . Of the plural documents sent to the transport roller pair  13 , only the uppermost one document is separated by the separation roller  13   b , and transported toward the register roller pair  14 . After the front end of this document is detected by the feeding sensor S 2  and then transported over a predetermined distance, the operation of the primary feeding drive means is stopped to halt the rotational driving of the transport roller pair  13  and the pickup roller  12 , thus completing primary feeding. The document is stopped, with its front end being compressed by the nip of the register roller pair  14 , and with a warp being formed at the front end. 
     A predetermined time after completion of primary feeding, secondary feeding is started. That is, the transport roller pair  13 , the register roller pair  14 , and the outlet roller pair  15  are rotationally driven by the operation of secondary feeding drive means (not shown). The document is transported toward the image reading position R and the outlet roller pair  15  by the register roller pair  14 , and then finally let out onto the document receiving tray  10 D by the outlet roller pair  15 . When the document outletting sensor S 3  provided downstream from the outlet roller pair  15  detects the passage of the rear end of the document, it can be determined that the image reading of one document has been completed. The document outletting sensor S 3  has the counting function of counting the number of the documents whenever it detects the passage of the rear end of the document. If the document setting detection sensor S 1  senses following documents, the transport of the second and subsequent documents is continued. The document, when passing the image reading position R, is transported while being pressed lightly against the surface of the document bearing board  106  by the white reference plate  17  and the document hold-down means  17   a . During this transport, the image surface of the document is relatively exposed and scanned by the exposure lamp  21  of the document exposure/image reading means  20  which is opposed to the document, with the document bearing board  106  being sandwiched therebetween. 
     More concretely, the first carriage C 1  and the second carriage C 2  are held at the aforementioned image reading stationary position when the image of the document is to be read by the document exposure/image reading means  20 . Light emitted from the exposure lamp  21  relatively scans the document passing the image reading position R. Reflected light from the document reaches the CCD  27  via the first mirror  23 , the second mirror  24 , the third mirror  25 , and the condenser lens  26 . As a result, the image of the document passing the image reading position R on the upper surface of the document bearing board  106  is relatively read and scanned by the document exposure/image reading means  20 , focused in a scaled-down size onto the CCD  27 , and converted into electrical signals thereby. 
     With further reference to FIG. 2, a paper feeding cassette  30  accommodating pieces of paper, image forming means  40  for forming an image on the paper, a fixing device  31 , and a paper transport passage  32  are disposed in the lower body  102 L of the copier body  102 . The paper feeding cassette  30  is housed in a lower end portion of the lower body  102 L so as to be withdrawable toward an operator in front of the copier  100 . A manual paper feeding tray  33  is disposed in a left-hand lower end portion of the lower body  102 L in FIG. 2 so as to be openable and closable. 
     The image forming means  40  disposed above the paper feeding cassette  30  includes a photoconductor drum  41 , and disposed around the photoconductor drum  41 , a main charger  42 , a laser scanning unit  43 , a developing device  44 , a transfer roller  45  as transfer means, and a cleaning device  50  according to the present invention. The paper transport passage  32  extends vertically beside (in FIG. 2, on the left side of) the photoconductor drum  41 . Because of this layout, a transfer zone is disposed nearly laterally of the circumferential surface of the photoconductor drum  41  (in FIG. 2, at a position nearly to the left of the circumferential surface and slightly below the center in the up-down direction of the circumferential surface), and the transfer roller  45  is in pressurized contact with the circumferential surface in the transfer zone. The cleaning device  50  is disposed above the photoconductor drum  41 , and has a lower end portion open downward toward the circumferential surface of the photoconductor drum  41 . The cleaning device  50  will be described in detail later on. 
     Two paper transport passages  32   a  and  32   b  merge with the upstream end of the paper transport passage  32 . The upstream end of the paper transport passage  32   a  is connected to the paper feeding cassette  30 , while the upstream end of the paper transport passage  32   b  is connected to the manual paper feeding tray  33 . In the lower body  102 L, there are also disposed a feed roller  30   a  for feeding pieces of paper P, accommodated in the paper feeding cassette  30 , one by one to the paper transport passage  32  via the paper transport passage  32   a , and a feed roller  33   a  for feeding pieces of paper P, set in the manual paper feeding tray  33 , one by one to the paper transport passage  32  via the paper transport passage  32   b . In the lower body  102 L, a register roller pair  34  is disposed in the paper transport passage  32  upstream from the photoconductor drum  41  and at the position of merger between the paper transport passages  32   a  and  32   b . On the paper transport passage  32 , the fixing device  31  is disposed downstream from the photoconductor drum  41 . The fixing device  31  includes a heat roller  31   a  and a pressure roller  31   b.    
     The paper transport passage  32  further extends vertically upwardly into the one-side portion connecting body  102 S, and branches into two paper transport passages  32   c  and  32   d  within the one-side portion connecting body  102 S. A branching pawl  35  is disposed at the position of branching of the paper transport passages  32   c  and  32   d . The paper transport passage  32   c  extends horizontally transversely (rightwardly in FIG. 2) from the position of branching, and is connected to the lower paper outlet opening  102 S b . The paper transport passage  32   d  extends obliquely upwardly in FIG. 2 from the position of branching, then extends horizontally transversely (rightwardly in FIG.  2 ), and is connected to the upper paper outlet opening  102 S a . Within the one-side portion connecting body  102 S, a transport roller pair  36  is disposed directly upstream from the position of branching in the paper transport passage  32 . An outlet roller pair  37  is disposed at the downstream end of the paper transport passage  32   c  and at a position directly upstream from the lower paper outlet opening  102 S b . In the paper transport passage  32   d , a transport roller pair  38  is disposed directly downstream from the position of branching, and an outlet roller pair  39  is disposed at the downstream end of the paper transport passage  32   d  and at a position directly upstream from the upper paper outlet opening  102 S a . The branching pawl  35  is selectively switched by an actuator (not shown) between a first position indicated by solid lines in FIG. 2 and a second position (not shown). 
     In the image forming means  40 , the photoconductor drum  41  comprises a positively chargeable a-Si-based photoconductor drum, and is rotationally driven by drive means (not shown) clockwise in FIG. 2 at a speed of 200 mm/sec. The circumferential surface of the photoconductor drum  41  is uniformly charged to +250 V by a corona discharge generated from the main charger  42  having a high voltage of 5 KV applied thereto. On the uniformly charged circumferential surface of the photoconductor drum  41 , an electrostatic latent image comprising portions of a light potential of +10 V and a dark potential of +250 V is formed by laser light thrown from the laser scanning unit  43  in correspondence with the document image read by the CCD  27 . In accordance with the rotation of the photoconductor drum  41 , the electrostatic latent image is moved to a development zone formed by the photoconductor drum  41  in cooperation with a development sleeve to be described later on. The developing device  44  has a developing roller  44   a , and the developing roller  44   a  has a development sleeve of stainless steel and a stationary magnet disposed within the development sleeve. In the development zone, the circumferential surface of the development sleeve is opposed to the circumferential surface of the photoconductor drum  41  with a clearance of 300 μm. The development sleeve is rotationally driven by drive means (not shown) so as to be rotationally moved in the development zone at a speed of 360 mm/second in the same direction as the photoconductor drum  41 . The interior of the developing device  44  is filled with a positively charged magnetic toner having a volume averaged particle size of 9 μm (a median size by a coulter counter). A thin layer of the toner is formed on the circumferential surface of the development sleeve by a magnetic blade (not shown). A developing bias voltage, which comprises a direct current voltage of +100 V and an alternating current electric field with a frequency of 2 KHZ and a peak-to-peak voltage of 2 KV superimposed thereon, is applied to the developing roller  44   a . The toner transported to the development zone is flied from the circumferential surface of the development sleeve by this developing bias to develop the electrostatic latent image formed on the circumferential surface of the photoconductor drum  41 . 
     The pieces of paper P, which have been fed one by one from the paper feeding cassette  30  or the manual paper feeding tray  33  toward the paper transport passage  32 , are moved in synchronism with the approach of the toner image formed on the circumferential surface of the photoconductor drum  41  to the transfer zone formed by the photoconductor drum  41  in cooperation with the transfer roller  45 . That is, the timing of transporting the paper is adjusted by the register roller pair  34  in synchronism with the approach, and the paper is transported through the transfer zone between the photoconductor drum  41  and the transfer roller  45  along the paper transport passage  32 . The paper P is passed through the transfer zone, with the front end of the paper P in alignment with the front end of the toner image formed on the circumferential surface of the photoconductor drum  41 , whereby most of the toner in the toner image is transferred onto the paper P. The untransferred toner, remaining on the circumferential surface of the photoconductor drum  41  without transferring onto the paper P, is removed, as will be described later, by the cleaning device  50  in accordance with the rotation of the photoconductor drum  41 . The paper P having the toner image transferred thereto is transported toward the fixing device  31  vertically upwardly along the paper transport passage  32  extending vertically beside the photoconductor drum  41 . During the passage of the paper P between the heat roller  31   a  and the pressure roller  31   b  of the fixing device  31 , the toner image transferred onto the paper P is fixed. 
     The paper P having the toner image fixed is further transported vertically upwardly along the paper transport passage  32 . If the branching pawl  35  is switched to the first position indicated by the solid lines in FIG. 2, the paper P is introduced into the paper transport passage  32   c  by the transport roller pair  36 , and let out by the outlet roller pair  37  onto the lower paper receiving tray  104   b  of the paper stack space portion  104  through the lower paper outlet opening  102 S b . If the branching pawl  35  is switched to the second position (not shown), on the other hand, the paper P is introduced into the paper transport passage  32   d  by the transport roller pairs  36  and  38 , and let out by the outlet roller pair  39  onto the upper paper receiving tray  104   a  of the paper stack space portion  104  through the upper paper outlet opening  102 S a.    
     Next, an embodiment of the cleaning device  50  constructed in accordance with the present invention will be described in detail with reference to FIG.  4 . The cleaning device  50  has a housing  51  disposed above the photoconductor drum  41  and having an opening portion open downward toward the circumferential surface of the photoconductor drum  41 . In more concrete terms, the housing  51  includes a top wall  51   a  extending with a predetermined width in the axial direction of the photoconductor drum  41  (in a direction perpendicular to the sheet face of FIG.  4 ), a pair of side walls  51   b  (only one of the side walls  51   b  is shown in FIG. 4) extending downwardly from opposite side edges in the fore-aft direction of the top wall  51   a  (in the direction perpendicular to the sheet face of FIG.  4 ), an upstream end wall  51   c  extending in the fore-aft direction between one end of the side wall  51   b  and one end of the other side wall  51   b  located upstream in the direction of rotation of the photoconductor drum  41  (these ends are left ends in FIG.  4 ), and a downstream end wall  51   d  extending in the fore-aft direction between the other end of the side wall  51   b  and the other end of the other side wall  51   b  located downstream in the direction of rotation of the photoconductor drum  41  (these ends are right ends in FIG.  4 ). The opening portion of the housing  51  is formed by the lower ends of the respective side walls  51   b , the upstream end wall  51   c  and the downstream end wall  51   d  of the housing  51 , the lower ends being opposed to the circumferential surface of the photoconductor drum  41 . 
     Within the housing  51 , there are provided a cleaning blade  52  for removing the toner remaining on the circumferential surface of the photoconductor drum  41 , and a cleaning roller  53  for cleaning the circumferential surface of the photoconductor drum  41  by sliding over, rubbing against and polishing it. The cleaning blade  52  is disposed in the housing  51  so as to be located in the opening portion of the housing  51  at a position downstream in the direction of rotation of the photoconductor drum  41  (i.e. clockwise in FIG.  4 ). The cleaning roller  53  is disposed in the housing  51  so as to be located in the opening portion of the housing  51  at a position upstream from the cleaning blade  52  in the direction of rotation of the photoconductor drum  41 . Within the housing  51 , there are also disposed a spiral roller  54 , as toner outletting spiral means, for letting the toner recovered into the housing  51  (in other words, cleaning toner) out of the housing  51 , accordingly, out of the cleaning device  50 , and a scraper  55  for scraping off the toner adhering to the surface of the cleaning roller  53 . The spiral roller  54  is disposed above and spaced from the cleaning blade  52 . Within the housing  51 , a partition wall  56  is disposed between the cleaning blade  52  and the spiral roller  54 , and a toner movement space  57  for moving the toner recovered into the housing  51  is formed between the front end  56   a  of the partition wall  56  and the circumferential surface of the cleaning roller  53 . A seal blade  58  for preventing leakage of the toner recovered into the housing  51  to the outside is disposed on the lower end surface of the upstream end wall  51   c  of the housing  51 . 
     The cleaning blade  52  of a strip shape having a constant width and a constant thickness has a base end region in its width direction integrally fastened to the lower surface of a batten-shaped metallic mounting member  52   a  by a suitable fastening means, for example, adhesion. The mounting member  52   a  is secured to the lower end surface of the downstream end wall  51   d  of the housing  51  by a suitable fastening means, for example, a screw. Thus, the cleaning blade  52  is mounted to the housing  51  via the mounting member  52   a , and extends in the axial direction of the photoconductor drum  41 . The lower end surface of the downstream end wall  51   d  of the housing  51  is inclined downwardly toward the upstream end wall  51   c , accordingly, in a direction approaching the circumferential surface of the photoconductor drum  41 . Thus, the cleaning blade  52  is also inclined downward toward the circumferential surface of the photoconductor drum  41 . The cleaning blade  52 , which comprises synthetic rubber having suitable hardness, polyurethane rubber with JIS hardness of 78° in the embodiment, has a thickness set at 2.0 mm and a length of extension from the front end of the mounting member  52   a  (i.e., the length from the front end of the mounting member  52   a  to the free end of the cleaning blade  52 ) set at 10.0 mm. The front end portion of the cleaning blade  52  has its front end directed in a direction opposite to the direction of rotation of the photoconductor drum  41 , and brought into pressurized contact with the circumferential surface of the photoconductor drum  41 . The amount of relative bite of the cleaning blade  52  into the photoconductor (i.e., the amount of elastic deformation of the photoconductor) at the site of pressurized contact with the circumferential surface of the photoconductor drum  41  is set at 1.5 mm. The cleaning blade  52  is mounted at an angle of 22° in the embodiment so as to make an acute angle with the tangent to the site of pressurized contact of the cleaning blade  52  with the circumferential surface of the photoconductor drum  41 , when the photoconductor drum  41  is viewed in the axial direction (in the direction perpendicular to the sheet face of FIG.  4 ). The site of pressurized contact of the cleaning blade  52  with the circumferential surface of the photoconductor drum  41 , when the photoconductor drum  41  is viewed in the axial direction, exists directly downstream from the summit of the circumferential surface of the photoconductor drum  41 , in the embodiment shown in FIG.  4 . The force of pressurized contact of the cleaning blade  52  with the circumferential surface of the photoconductor drum  41  is set at 5 g/mm. 
     The cleaning roller  53  comprises a metallic shaft, and synthetic rubber covering the periphery of the shaft to a predetermined thickness. In the embodiment, the cleaning roller  53  comprises a metallic shaft  53   a  having a circular section with a diameter of 10 mm, and a foam  53   b  of EPDM rubber (Asker C hardness 55°) covering the periphery of the shaft with a thickness of 2.5 mm. The synthetic rubber layer of the cleaning roller  53  is not limited to the above embodiment, but may be formed of other synthetic rubber or foamed synthetic rubber, and the preferred material has an Asker C hardness of 10° to 90°. The cleaning roller  53  is rotatably supported between the respective side walls  51   b  of the housing  51 , and its circumferential surface is in pressurized contact with the circumferential surface of the photoconductor drum  41 . The circumferential surface of the cleaning roller  53  is rotationally driven by drive means (not shown) so as to be rotationally moved in the same direction as the circumferential surface of the photoconductor drum  41  at the site of contact of the circumferential surface of the cleaning roller  53  with the circumferential surface of the photoconductor drum  41 . That is, in FIG. 4, the photoconductor drum  41  is rotationally driven clockwise, while the cleaning roller  53  is rotationally driven counterclockwise. The peripheral speed of the cleaning roller  53  is set at 1.2 times the peripheral speed of the photoconductor drum  41 . The site of pressurized contact of the cleaning roller  53  with the circumferential surface of the photoconductor drum  41 , when the photoconductor drum  41  is viewed in the axial direction, exists directly upstream from the summit of the circumferential surface of the photoconductor drum  41 , in the embodiment shown in FIG.  4 . When the photoconductor drum  41  is viewed in the axial direction, a predetermined gap for recovering the toner recovered from the circumferential surface of the photoconductor drum  41  into the housing  51  is provided between the site of pressurized contact of the cleaning roller  53  with the circumferential surface of the photoconductor drum  41  and the site of pressurized contact of the cleaning blade  52  with the circumferential surface of the photoconductor drum  41 . a 
     A mounting stay  59  comprising a metal plate is disposed between the respective side walls  51   b  of the housing  51  and above the cleaning roller  53 . The mounting stay  59  has a strip-shaped flat plate portion having a constant width, a flange portion extending downwardly from one side edge of the flat plate portion (the one side edge located upstream in the direction of rotation of the photoconductor drum  41 ), and an inclined flange portion  59   a  extending obliquely downwardly from the other side edge of the flat plate portion (the other side edge located downstream in the direction of rotation of the photoconductor drum  41 ) away from the flange portion. The strip-shaped scraper  55  having a constant width and a constant thickness has a base end region in its width direction fastened to the upper surface of the inclined flange portion  59   a  of the mounting stay  59  by a suitable fastening means, for example, adhesion. The scraper  55  comprising a metallic thin plate having suitable elasticity, an elastic thin plate of stainless steel (sus304) 0.05 mm thick in the embodiment, extends from the inclined flange portion  59   a  of the mounting stay  59 . A front end portion of the scraper  55  has its front end directed in a direction opposite to the direction of rotation of the cleaning roller  53 , and kept in pressurized contact with the circumferential surface of the cleaning roller  53 , downstream from the site of pressurized contact between the circumferential surface of the cleaning roller  53  and the circumferential surface of the photoconductor drum  41  in the direction of rotation of the cleaning roller  53 . In the embodiment, the scraper  55  is disposed so as to be capable of scraping off the toner adhering to the circumferential surface of the cleaning roller  53  into the gap between the cleaning roller  53  and the spiral roller  54 . That is, the scraper  55  extends in the direction of a tangent to the circumferential surface of the cleaning roller  53 , the tangent intersecting nearly perpendicularly to a straight line connecting the center of rotation of the cleaning roller  53  to the center of rotation of the spiral roller  54 . The site of pressurized contact of the scraper  55  with the circumferential surface of the cleaning roller  53  is existent directly above a position on the circumferential surface of the cleaning roller  53 , the position being closest to a rotation region of the spiral roller  54  (to be described later on), and is also existent directly downstream in the direction of rotation of the cleaning roller  53 . That is, the scraper  55  extends in the direction of the tangent, with the front end of the scraper  55  being directed toward the position on the circumferential surface of the cleaning roller  53 , the position most approaching the rotation region of the spiral roller  54 . 
     The spiral roller  54  disposed above and apart from the cleaning blade  52  has a shaft  54   a  having a circular section, and a spiral blade  54   b  extending axially on the outer peripheral surface of the shaft  54   a . In a partial region of the shaft  54   a , a plate blade for agitation is also disposed which extends radially outwardly from the outer peripheral surface of the shaft  54   a . The spiral roller  54 , which can be formed of a suitable synthetic resin or metal, is rotatably supported between the side walls  51   b  of the housing  51 , and is rotationally driven counterclockwise in FIG. 4 by drive means (not shown). The diameter of the spiral roller  54 , i.e., the diameter of the spiral blade  54   b , is the same as the diameter of the locus of rotation of the radially outward front end of the spiral blade  54   b , and a cylindrical region surrounded by the loci of rotation defines the rotation region of the spiral roller  54 . Thus, the diameter of the rotation region is the same as the diameter of the spiral blade  54   b . The spiral roller  54  is disposed practically downstream from the cleaning roller  53  in the direction of rotation of the photoconductor drum  41 , and the center of rotation of the spiral roller  54  is located above the center of rotation of the cleaning roller  53 . The circumferential surface of the rotation region of the spiral roller  54  is oppose to the circumferential surface of the cleaning roller  53  with spacing provided practically downstream in the direction of rotation of the photoconductor drum  41 . The axes of the cleaning roller  53  and the spiral roller  54  are parallel to the axis of the photoconductor drum  41 . 
     The aforementioned partition wall  56  is formed in a space region, where the spiral roller  54  and the cleaning blade  52  are opposed in the up-down direction, so as to extend from an inner surface of the lower end portion of the downstream end wall  51   d  of the housing  51  toward the interior of the housing  51  and toward the upstream end wall  51   c  of the housing  51 . In other words, when the rotation region of the spiral roller  54  is viewed in the vertical direction, the partition wall  56  extends out from the downstream end toward the upstream end of the rotation region in the direction of rotation of the photoconductor drum  41 . The upper surface of the partition wall  56  is opposed, with a nearly constant slight gap, to the outer peripheral surface of the rotation region of the spiral blade  54   b  of the spiral roller  54 , while the lower surface of the partition wall  56  is opposed, with a slight gap, to the upper surface of the cleaning blade  52 . These gaps should preferably be minimal unless problematical for practical use. Most of the space region where the spiral roller  54  and the cleaning blade  52  are opposed in the up-down direction is accounted for by the partition wall  56 . Between the front end  56   a  of the partition wall  56  and the circumferential surface of the cleaning roller  53 , a toner movement space  57  is formed for moving the toner recovered into the housing  51 . The toner movement space  57  continues into the aforementioned space formed above the region between the site of pressurized contact of the cleaning roller  53  and the site of pressurized contact of the cleaning blade  52  with the circumferential surface of the photoconductor drum  41 . The partition wall  56  blocks most of the space between the spiral roller  54  and the cleaning blade  52 , except at least the toner movement space  57 . 
     The aforesaid seal blade  58  is in pressurized contact with the circumferential surface of the photoconductor drum  41  upstream from the site of pressurized contact of the cleaning roller  53  with the photoconductor drum  41  in the direction of rotation of the photoconductor drum  41 . The seal blade  58  has the front end disposed practically in the direction of rotation of the photoconductor drum  41 . Also, when the photoconductor drum  41  is viewed in the axial direction, the seal blade  58  is disposed so as to make an acute angle with the tangent to the site of pressurized contact of the seal blade  58  with the circumferential surface of the photoconductor drum  41 . As shown in FIG. 4, the seal blade  58  in the embodiment is inclined slightly downwardly toward the circumferential surface of the photoconductor drum  41 . 
     When the copying action of the copier  100  is performed in the aforementioned manner, the electrostatic latent image formed on the circumferential surface of the rotating photoconductor drum  41  is developed with the toner, and the developed toner image is transferred onto the paper P by the transfer roller  45 . The untransferred toner remaining on the circumferential surface of the photoconductor drum  41  is rotationally moved toward the cleaning device  50  in accordance with the rotation of the photoconductor drum  41 . The cleaning roller  53  of the cleaning device  50  functions as a polishing roller when the circumferential surface of the cleaning roller  53  makes pressurized contact with the circumferential surface of the photoconductor drum  41  via the toner and slides over and rubs the circumferential surface of the photoconductor drum  41 . Thus, the cleaning roller  53  can maintain the circumferential surface of the photoconductor drum  41  always in a clean state. That is, the cleaning roller  53  strips off part of the toner remaining on the circumferential surface of the photoconductor drum  41 , or mechanically disturbs the toner, if does not remove it, thereby bringing the toner into a state easily detachable from the circumferential surface, namely, an easily cleanable state. Moreover, the cleaning roller  53  prevents a fusion of the toner from occurring and growing, with the additives released from the toner serving as a core. Furthermore, the cleaning roller  53  removes a filming layer of the toner formed on the circumferential surface of the photoconductor drum  41 . If the photoconductor drum  41  comprises an a-Si-based photoconductor drum, the cleaning roller  53  can maintain the circumferential surface of the photoconductor drum  41  always clean by, for example, removing a deteriorated surface layer due to ozone from the circumferential surface of the photoconductor drum  41 . The toner deposited on the surface of the cleaning roller  53  can be scraped off by the scraper  55 . Thus, the cleaning roller  53  can be constantly restored to a clean circumferential surface, and so can retain the desired cleaning performance for a long period of time. 
     In the foregoing copier  100 , the photoconductor drum  41  comprises an a-Si-based photoconductor drum, and the peripheral speed of the cleaning roller  53  is greater than the peripheral speed of the photoconductor drum  41 . According to these features, even when the a-Si-based photoconductor drum apt to cause image distortion is used, the circumferential surface of the photoconductor drum  41  can be polished by sliding and rubbing by the circumferential surface of the cleaning roller  53  and the recovered toner adhering to the circumferential surface of the cleaning roller  53 . Thus, image distortion, filming of the toner, and toner deposition, which occur on the circumferential surface of the photoconductor drum  41 , can be prevented, and the maintenance cycle can be prolonged. Furthermore, the peripheral speed of the cleaning roller  53  is made higher than the peripheral speed of the photoconductor drum  41 , whereby the above polishing action can be performed more effectively. In the above embodiment of the present invention, the peripheral speed of the cleaning roller  53  is set at 1.2 times the peripheral speed of the photoconductor drum  41 , but this is not restrictive, and is preferably set at 1.05 to 2.5 times the latter peripheral speed. If the peripheral speed of the cleaning roller  53  is less than 1.05 times the peripheral speed of the photoconductor drum  41 , there will be a decline in the cleaning effect of the cleaning roller  53  on the toner deposited on the circumferential surface of the photoconductor drum  41 . Hence, black spot-like copy smudges, filming of toner, and image distortion on the a-Si-based photoconductor drum tend to occur easily. If the peripheral speed of the cleaning roller  53  is more than 2.5 times the peripheral speed of the photoconductor drum  41 , there will be an impediment to the smooth rotation of the photoconductor drum  41 , and jitter due to uneven rotations is liable to occur. These problems are solved by setting the peripheral speed of the cleaning roller  53  to be within the range of 1.05 to 2.5 times the peripheral speed of the photoconductor drum  41 . The remaining toner, which has not been removed from the circumferential surface of the photoconductor drum  41  by the cleaning roller  53 , is completely removed by the cleaning blade  52  disposed downstream from the cleaning roller  53 . 
     Within the housing  51 , the spiral roller  54  for outletting the toner recovered into the housing  51  is disposed above the cleaning blade  52 , the partition wall  56  is disposed between the cleaning blade  52  and the spiral roller  54 , and the toner movement space  57  for moving the toner recovered into the housing  51  is formed between the front end  56   a  of the partition wall  56  and the circumferential surface of the cleaning roller  53 . According to this construction, the cleaning roller  53 , the cleaning blade  52  and the spiral roller  54  can be accommodated in the housing  51  compactly. As a result, a compact cleaning device  50  and a compact copier  100  can be obtained. Particularly, it becomes possible to promptly flow the recovered toner to the spiral roller  54 , which exists above the partition wall  56 , through the toner movement space  57  between the front end  56   a  of the partition wall  56  and the cleaning roller  53 . Thus, toner agglomeration and toner blocking can be prevented until the recovered toner is withdrawn to the outside. Also, the presence of the partition wall  56  prevents the sinking of the recovered toner under its own weight. The recovered toner can be promptly transported and let out of the cleaning device  50  by the spiral roller  54  without being leaked to the outside. 
     The act of letting out the recovered toner will be described in further detail. The toner recovered into the housing  51  by the cleaning roller  53  and the cleaning blade  52  is rendered stagnant in a lower part of the toner movement space  57 , and gradually increased. Most of the space between the cleaning blade  52  and the spiral roller  54 , which is the space above the cleaning blade  52  and the space below the spiral roller  54 , is closed by the partition wall  56 , except at least the toner movement space  57 . Thus, the toner recovered into the housing  51  is smoothly and promptly raised toward the rotation region of the spiral roller  54  through the toner movement space  57  with the assistance of the rotating and transporting action of the circumferential surface of the cleaning roller  53 , without stagnating on the cleaning blade  52 , and is advanced into the rotation region of the spiral roller  54 . The recovered toner advanced into the rotation region of the spiral roller  54  is prevented from sinking downward under its own weight, because the lower side of the rotation region is supported by the partition wall  56 . Thus, the recovered toner is promptly transported and let out by the spiral roller  54 , without leaking to the outside, into a toner recovery container (not shown) disposed outside the cleaning device  50 . Moreover, toner agglomeration and the formation of toner blocks can be prevented until the recovered toner is withdrawn to the outside. 
     The circumferential surface of the cleaning roller  53  is rotationally moved in the same direction as the circumferential surface of the photoconductor drum  41  at the site of pressurized contact between these circumferential surfaces. The scraper  55  is disposed within the housing  51 , and the front end portion of the scraper  55  is kept in pressurized contact with the circumferential surface of the cleaning roller  53  downstream from the site of pressurized contact between the circumferential surfaces in the direction of rotation of the cleaning roller  53 , with the front end of the scraper  55  being directed in a direction opposite to the direction of rotation of the cleaning roller  53 . According to these features, the recovered toner adhering to the circumferential surface of the cleaning roller  53  is effectively separated by the front end portion of the scraper  55  contacted under pressure with the circumferential surface of the cleaning roller  53  so as to be opposed to the direction of rotation of the circumferential surface of the cleaning roller  53 . The recovered toner adhering to the circumferential surface of the cleaning roller  53  includes not only the recovered toner, which has been moved onto the circumferential surface of the cleaning roller  53  as a result of the polishing of the circumferential surface of the photoconductor drum  41  slid over and rubbed against by the circumferential surface of the cleaning roller  53 , but also part of the recovered toner which has been removed from the circumferential surface of the photoconductor drum  41  by the cleaning blade  52 , brought into contact with the circumferential surface of the cleaning roller  53 , and thereby deposited on the circumferential surface of the cleaning roller  53 . 
     In the above-described embodiment of the present invention, the scraper  55  is disposed so as to be capable of scraping off the toner adhering to the circumferential surface of the cleaning roller  53  to the space between the cleaning roller  53  and the spiral roller  54 . According to this feature, the recovered toner that has been scraped off the circumferential surface of the cleaning roller  53  by the scraper  55  can be directed to a position where the spiral roller  54  can easily receive the recovered toner. Thus, the recovered toner can be promptly fed into the rotation region of the spiral roller  54 . As a result, the recovered toner can be transported and let out with high efficiency to the outside of the cleaning device  50 . The toner scraped off to the space between the cleaning roller  53  and the spiral roller  54  is inhibited from falling toward the photoconductor drum  41 , by the recovered toner rising from below. As a result, the scraped toner is moved toward the spiral roller  54  together with the recovered toner rising from below, and transported and taken out of the cleaning device  50  highly efficiently by the spiral roller  54 . There is another embodiment in which the scraper  55  is disposed so as to be capable of scraping off the toner, which has adhered to the circumferential surface of the cleaning roller  53 , toward the rotation region of the spiral roller  54 . In this embodiment, the scraper  55  is disposed such that its front end is opposed to the rotation region of the spiral roller  54 . Thus, the above actions and effects can be achieved even more efficiently. In the aforementioned embodiment, the direction of mounting of the scraper  55  is tangent to the site of pressurized contact of the scraper  55  with the circumferential surface of the cleaning roller  53 , but this is not restrictive, and the scraper  55  may have a predetermined angle to the tangent to the site of pressurized contact. The thickness of the scraper  55  is preferably within the range of 0.02 to 2.0 mm. In the aforementioned embodiment, the scraper  55  is formed of SUS304 having weak magnetism, but this is not restrictive, and the scraper  55  may be formed of a nonmagnetic SUS plate, a blade plate of any of various resins or metals, or a rubber blade plate. 
     When the rotation region of the spiral roller  54  is viewed in the vertical direction, the partition wall  56  extends out from the downstream end toward the upstream end of the rotation region in the direction of rotation of the photoconductor drum  41 . When the rotation region is viewed in the vertical direction, the effective length of shielding, A, of the rotation region by the partition wall  56  is preferably 30% or more of the diameter of the rotation region. As will be easily understood by reference to FIG. 5, this effective shielding length A means what percentage of the diameter of the rotation region, B, the partition wall  56  shields in the direction from the base end of the diameter B toward the upstream end of the diameter B by extending out from the base end toward the upstream end, when the rotation region is viewed in the vertical direction, the base end defining one end of the diameter B of the rotation region and being the downstream end (the right end in FIG. 5) in the direction of rotation of the photoconductor drum  41 , and the upstream end (the left end in FIG. 5) defining the other end of the diameter B of the rotation region. If the diameter B is shielded over the range from the base end up to the upstream end, the effective shielding length A is 100%. If the effective shielding length A is 30% or more, the sinking of the recovered toner, which has risen from the toner movement space  57 , can be effectively prevented, and toner agglomeration and formation of toner blocks can be prevented until the recovered toner is withdrawn to the outside. During this process, the prompt transport and withdrawal, by the spiral roller  54 , of the recovered toner to the outside of the cleaning device  50  can be effectively performed for practical use, without leakage of the recovered toner to the outside. If the effective shielding length A is less than 30%, the sinking of the toner to the lower part of the toner movement space  57  is slightly increased, making the toner tend to stagnate. In the aforementioned embodiment of the present invention, the front end  56   a  of the partition wall  56  is disposed nearly vertically below the center of rotation of the spiral roller  54 . This arrangement means that the effective shielding length A is about 50%. If the effective shielding length A is set at nearly 50%, the sinking of the recovered toner, which has moved toward the spiral roller  54 , can be prevented particularly effectively, and toner agglomeration and formation of toner blocks can be prevented until the recovered toner is withdrawn to the outside. During this process, the prompt transport and withdrawal, by the spiral roller  54 , of the recovered toner to the outside of the cleaning device  50  can be effectively performed for practical use, without leakage of the recovered toner to the outside. 
     The horizontal distance C (see FIG. 5) at which the front end  56   a  of the partition wall  56  and the circumferential surface of the cleaning roller  53  maximally approach each other should preferably be 2 mm or more. According to this feature, the recovered toner satisfactorily rises toward the upper part of the toner movement space  57  without stagnating. As a result, the prompt transport and withdrawal, by the spiral roller  54 , of the recovered toner to the outside of the cleaning device  50  can be effectively performed for practical use. If the horizontal distance C for maximal approach is less than 2 mm, the rising of the recovered toner toward the upper part of the toner movement space  57  is slightly poor, and the recovered toner tends to be stagnant. In the above embodiment of the present invention, the horizontal distance C for maximal approach is 7 mm, which makes it possible to achieve the aforementioned actions effectively for practical use. 
     The distance D at which the circumferential surface of the cleaning roller  53  and the rotation region of the spiral roller  54  maximally approach each other (see FIG. 5) is preferably 3 mm or less. According to this feature, there is an increase in the ratio of the recovered toner directly falling toward the spiral roller  54  to the recovered toner scraped off the circumferential surface of the cleaning roller  53  by the scraper  55 . This makes it possible, for practical use, to move the recovered toner toward the spiral roller  54  highly efficiently, and transport and withdraw it to the outside of the cleaning device  50  with better efficiency. In the present embodiment, the distance D for maximal approach is set at 1.5 mm, enabling the above-mentioned actions to be achieved effectively for practical use. 
     According to the copier  100  equipped with the foregoing cleaning device  50 , the aforementioned actions and effects by the cleaning device  50  are obtained, and the cleaning device  50  can be downsized. Thus, the photoconductor drum  41  and the copier  100  can be easily scaled down. Moreover, increased allowance is made for the installation space for imaging elements disposed around the photoconductor drum  41 , such as the developing device  44 , main charger  42  and transfer roller  45 . Thus, the copier  100  can be designed easily. 
     The copier  100  comprises the copier body  102 , the image forming means  40  disposed in the body  102  and including the photoconductor drum  41  and the cleaning device  50 , the document exposure/image reading means  20  disposed within the upper end portion of the body  102  and above the image forming means  40 , the paper stack space portion  104  disposed in the region between the image forming means  40  and the document exposure/image reading means  20  in the body  102 , and the paper transport passage  32  extending vertically beside the photoconductor drum  41  and adapted to guide the fed paper P to the paper stack space portion  104 . According to the so constructed in-body paper delivery type copier  100 , the cleaning device  50  can be downsized. Thus, the photoconductor drum  41  can be made compact. As a result, the copier  100  can be easily scaled down. Moreover, increased allowance is made for the installation space for the imaging elements disposed around the photoconductor drum  41 , such as the developing device  44 , main charger  42  and transfer roller  45 . Thus, the copier  100  can be designed easily. 
     The toner used in the copier  100  is preferably a magnetic toner. For the reasons stated earlier, the magnetic toner has the property of easily depositing on the circumferential surface of the photoconductor drum  41  as compared with a nonmagnetic toner. However, the provision of the cleaning device  50  can effectively eliminate the deposition of the toner on the circumferential surface of the photoconductor drum  41 , thus preventing the occurrence of black spot-like copy smudges, corresponding to toner deposits, on the surface of the paper P which is a copy. Moreover, a high copying speed can be achieved, with satisfactory image formation being ensured. 
     The image forming apparatus equipped with the cleaning device  50  is composed of an in-body paper delivery type copier  100  according to the above-described embodiment. However, the present invention can be applied to a copier or laser printer in other embodiment, especially a copier or laser printer having a paper transport passage extending vertically beside a photoconductor drum. In the aforementioned embodiment, moreover, the most typical paper is exemplified as a material on which to record an image. The paper may be a sheet member capable of having an image recorded thereon, so that the paper refers to a sheet member capable of having an image recorded thereon.