JP3723069B2 - Image carrier unit and image forming apparatus having the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an image carrier unit including a charging roller, an image carrier, and a cleaning device that cleans the surface of the image carrier, and an image forming apparatus including the image carrier unit.
[0002]
[Prior art]
  In an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, etc., before forming an electrostatic latent image on the surface of a photoconductor as an image carrier, the photoconductor is uniformly formed by various methods. It is charged.
  As one of the charging methods, in recent years, a charging roller formed in a roller shape with a conductive member is brought into contact with the surface of the photosensitive member, and in that state, a voltage is applied between the charging roller and the photosensitive member, Contact charging devices that charge the surface of a photoconductor have been put to practical use because they have the advantage of lowering ozone and lowering power.
[0003]
  However, since the charging roller used in such a contact charging device has an elastic roller portion formed of conductive rubber on the outside of a metal core, for example, the elastic roller portion is photosensitive. If it is left for a long time in a state of being pressed against the surface of the body, a substance (for example, a plasticizer) contained in the elastic roller portion oozes out on the surface, which stains the surface of the photoreceptor. That happened.
[0004]
  In the case of contact charging, charging is performed in a state where a charging member such as a charging roller is in contact with the surface of an image carrier such as a photosensitive member. When the toner or the like is contaminated by transferring to the surface of the charging member, the charging performance may be deteriorated due to the contamination.
[0005]
  Therefore, in order to solve such a problem, a convex portion forming member for forming a convex portion made of a spacer or a tape having a predetermined thickness is attached to both ends of the elastic roller portion of the charging roller, thereby charging A non-contact charging device has been proposed in which the other portions except for the convex-forming members at both ends of the roller are in non-contact with the surface of the photoconductor, and the photoconductor is charged in this state ( For example, refer to JP-A-3-240076, JP-A-4-360167, JP-A-5-107871, etc.).
[0006]
  According to this non-contact charging device, the charging effective area which is the inner region of the convex portion forming members on both sides of the charging roller does not contact the photoconductor, so that the elastic roller portion of the charging roller which is a drawback of the above-described contact charging device It is possible to solve the problem that the substance contained in the toner adheres to the photoconductor and the adhering material such as toner adhering to the surface of the photoconductor easily transfers to the surface of the charging roller.
[0007]
  By the way, in an electrophotographic image forming apparatus that uses toner for image formation, transfer residual toner remaining on the surface of the photoreceptor after the image is transferred to the transfer paper is transferred to the surface of the charging roller or the above-described convex forming member. 12, the surface of the photosensitive drum 105 is brought close to the cleaning blade 147 in sliding contact as shown in FIG. 12, and the entrance seal 101 having a length substantially the same as that of the cleaning blade 147 and the entrance seal 101 Side seals 102 and 102 (for example, only one end side is shown in FIG. 12) are provided at both ends in the longitudinal direction.
  This prevents the toner from leaking to the outside of the side seals 102 on both sides.
[0008]
[Problems to be solved by the invention]
  However, even if the side seals 102 and 102 are provided at both ends of the cleaning blade 147 that is in sliding contact with the surface of the photosensitive drum 105 as described above, the side seals 102 and 102 (only one side is shown, while the other side is shown. 13 are located at the positions shown in FIG. 13, and both ends of the effective cleaning width of the surface of the photosensitive drum 105 cleaned by the cleaning blade 147 (on the opposite side to the side shown in FIG. 13). The end portion is in a completely target positional relationship with the illustrated positional relationship), but inconvenience occurred when it was inside the convex portion forming member 118.
[0009]
  In other words, in this case, the toner on the photosensitive drum 105 is restricted from leaking outside from the side seals 102 and 102 on both sides, but the toner that has not been completely removed corresponding to the end of the cleaning blade 147. Since some of the toner may leak onto the photosensitive drum 105 as shown in the figure, when the toner on the photosensitive drum 105 is transferred to the charging roller 114, the charging roller 114 becomes dirty and the charging performance deteriorates. There was a problem.
[0010]
  The present invention has been made in view of the above-described problems. When toner or the like adhering to the surface of an image carrier such as a photoreceptor is cleaned by a cleaning device, a part of the toner or the like is removed from the charging roller. The object is to prevent adhesion to parts that affect the charging performance.
[0011]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides a charging roller and,With image carrier,A cleaning device for cleaning the surface of the image carrier, and forming convex portions at both ends of the charging roller in the circumferential direction with a predetermined width, and forming the convex portions at both ends of the surface of the image carrier. To form an air gap between the inside of the convex portions on both sides of the charging roller and the surface of the image carrier, and discharge in the air gap between the charging roller and the image carrier. In the image carrier unit for charging the surface of the image carrier to a predetermined potential by
  The cleaning deviceTheBoth ends of the effective cleaning width for cleaning the surface of the image carrier are not positioned on the inner side of the portions where the convex portions on both sides of the surface of the image carrier are in contact with each other.And a convex cleaning means for simultaneously cleaning the surface of each convex portion on both sides of the charging roller and the entire charging effective area of the charging roller.It is a thing.
[0012]
AndEach of the convex portions may be formed continuously at both ends of the charging roller over the entire circumference in the circumferential direction so as not to have a step portion due to a seam in the middle.
[0013]
  AlsoAlso provided is an image forming apparatus comprising any of the above image carrier units.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
  First, an image carrier unit and a small printer including the image carrier unit, which are the basis of the present invention, will be described.
  FIG. 1 shows the present invention.The basis ofFIG. 2 is a schematic diagram for explaining the effective cleaning width of a cleaning device provided in a photoconductor unit as an image carrier unit, FIG. 2 is a configuration diagram showing the photoconductor unit, and FIG. FIG. 4 is a schematic diagram showing a part of the charging device and the photosensitive drum provided, and FIG. 4 is also a diagram illustrating one of the charging rollers in order to explain the joint portion of the convex forming member wound around both ends of the charging roller. FIG. 5 is a front view showing only the end side, and FIG. 5 is an overall configuration diagram showing a small color printer which is an image forming apparatus provided with a plurality of the photoreceptor units shown in FIG.
[0015]
  The color compact printer as the image forming apparatus shown in FIG. 5 is a four-drum full-color electrophotographic image forming apparatus, and in the apparatus main body 1, there are four image carrier unit photosensitive units 2A, 2B, 2C, and 2D are detachably attached to the apparatus main body 1, respectively.
  In this small printer, a transfer belt 3 is stretched between a plurality of rollers so as to be rotatable in a direction indicated by an arrow A at a substantially central position in the apparatus main body 1.
[0016]
  Then, the photosensitive unit 2A to the photosensitive drum 5 provided on each of the four photosensitive units 2A, 2B, 2C, and 2D are in contact with the upper surface of the transfer belt 3 in FIG. Each 2D is arranged.
  In correspondence with the photoreceptor units 2A to 2D, developing devices 10A to 10D having different toner colors are disposed.
[0017]
  A writing unit 6 is disposed above the photoreceptor units 2A to 2D, and a duplex unit 7 is disposed below.
  Further, this small printer is equipped with a reversing unit 8 that inverts and discharges the transfer paper P after image formation or conveys it to the duplex unit 7 on the left side of the apparatus main body 1 in FIG.
[0018]
  Between the transfer belt 3 and the reversing unit 8, there is provided a fixing device 9 for fixing the image of the transfer paper onto which the image has been transferred.
  A reversal conveyance path 20 is formed on the downstream side of the fixing device 9 in the conveyance direction of the transfer sheet, and the transfer sheet P conveyed there can be discharged onto a discharge tray 26 by a discharge roller pair 25. .
[0019]
  Further, in the lower part of the apparatus main body 1, paper feed cassettes 11 and 12 that can store transfer papers P of different sizes are arranged in two upper and lower stages.
  Further, a manual feed tray 13 is provided on the right side surface of the apparatus main body 1 so as to be openable and closable in the direction indicated by the arrow B, and the manual feed tray 13 is opened so that manual feeding can be performed therefrom.
[0020]
  The photoconductor units 2A to 2D are units having the same configuration, the photoconductor unit 2A forms an image corresponding to yellow, and the photoconductor unit 2B forms an image corresponding to magenta. 2C forms an image corresponding to the cyan color, and the photoreceptor unit 2D forms an image corresponding to the black color. They are arranged at intervals in the transfer paper conveyance direction.
[0021]
  The photosensitive units 2A to 2D include a photosensitive drum 5 that is an OPC drum type image carrier on which an electrostatic latent image is formed by exposure as shown in FIG. 2, and an elastic roller portion as shown in FIG. A charging device 4 having a charging roller 14 to which convex portion forming members 18 and 18 made of, for example, a tape material are attached, each of which forms a convex portion with a predetermined width on the outer periphery of both end portions of the peripheral portion 17; 14 are provided with pressure springs 19 and 19 for urging both ends of the photoconductor 14 toward the photosensitive drum 5.
[0022]
  The photoreceptor units 2A to 2D are formed in a unit shape as shown in FIG. 2 and can be attached to and detached from the apparatus main body 1 (FIG. 5). A cleaning blade 47, a brush roller 15, and a toner transport auger 48, which constitute a cleaning device that slides the tip to scrape off residual toner and the like adhering to the surface of the photosensitive drum 5 when it is rotated. A charging roller cleaner 49 is also provided integrally.
[0023]
  In addition, as shown in FIG. 1, the photoreceptor units 2 </ b> A to 2 </ b> D include an entrance seal 61 that is slightly shorter in the longitudinal direction than the cleaning blade 47, and a longitudinal direction of the entrance seal 61. Side seals 62 and 63 made of, for example, flocking seals are provided at both ends of the toner cartridge, respectively. Is not leaking to the outside.
[0024]
  Then, the toner scraped off from the surface of the photosensitive drum 5 by the cleaning blade 47 is moved to the toner transport auger 48 side by the brush roller 15 shown in FIG. 2 and recovered by rotating the toner transport auger 48. Waste toner is conveyed to a predetermined waste toner storage unit.
[0025]
  Further, a charging roller cleaner 49 made of, for example, a sponge is provided in contact with the effective charging area Ac (FIG. 3) on the surface of the elastic roller portion 17 of the charging roller 14, and the toner, dust, etc. floating in the machine are elastic by the charging roller cleaner 49. Even when the toner adheres to the surface of the roller portion 17, the toner, dust, etc. can be cleaned by rotating the charging roller.
[0026]
  The photoconductor units 2A to 2D are provided with a positioning main reference portion 51 as a reference for attaching and detaching the photoconductor units 2A to 2D with respect to the apparatus main body 1 (see FIG. 5). The sub-reference portion 53 is integrally provided on the bracket 50, and when the photoconductor units 2A to 2D are mounted on the apparatus main body 1, the photoconductor units 2A to 2D are surely placed at predetermined mounting positions by the reference portions. Can be positioned.
[0027]
  Each of the photosensitive drums 5 of the photosensitive units 2A to 2D rotates in the direction indicated by an arrow C in FIG. 2, and the linear speeds thereof are monochrome speed priority mode, monochrome image quality priority mode, color speed priority mode, and color image quality. It can be adjusted in three stages of 185 mm / sec, 125 mm / sec, and 62.5 mm / sec according to several modes such as a priority mode and a cardboard / OHP paper feeding mode.
  The photoconductor unit may be configured by removing the brush roller 15 from the configuration.
[0028]
  As shown in FIG. 3, the charging device 4 has the charging roller 14 brought into contact with the convex forming members 18, 18 at both ends thereof on the surface of the photosensitive drum 5, and the convex forming members on both sides of the charging roller 14. A gap G, which is a gap, is formed between the charging effective area Ac, which is a portion between the insides of 18 and 18, and the surface of the photosensitive drum 5, and a gap between the charging roller 14 and the photosensitive drum 5 is formed. The surface of the photosensitive drum 5 is charged to a predetermined potential by discharging.
[0029]
  The charging roller 14 of the charging device 4 is made of, for example, epichlorohydrin rubber at a portion excluding both ends of the outer peripheral surface of the cored bar 16 which is a metal shaft formed by, for example, SUM-Ni plating (steel surface is nickel-plated). The volume resistivity value is 1 × 10³~ 1x10⁸An elastic roller portion 17 having Ω · cm is formed.
[0030]
  On both ends of the elastic roller portion 17, convex portion forming members 18 and 18, which are pressure-sensitive adhesive sheets each having one surface made of polyester or polyethylene terephthalate, for example, are wound in the circumferential direction. ing.
[0031]
  And, as shown in FIG. 4, the convex portions forming members 18, 18 on both sides overlap the circumferential edges 18 a, 18 b, which are both ends in the circumferential direction, respectively. The adhesive surface side is fixed by sticking so that there is no portion where the convex portion forming member 18 does not exist in the axial direction of the roller indicated by the arrow J at all positions around the circumference.
  Therefore, as shown in the drawing, both end portions of each convex portion forming member 18 are cut obliquely so that the end edges 18a and 18b of the respective cut ends face each other.
[0032]
  As shown in FIG. 3, the charging device 4 is configured such that the charging roller 14 is brought into contact with the outer portions of the charging effective area Ac of the photosensitive drum 5 with the projecting portion forming members 18 and 18 at both ends. By applying a voltage from a power source (not shown) between the roller 14 and the photosensitive drum 5, the surface of the photosensitive drum 5 is charged.
[0033]
  In the charging roller 14, both end portions of the cored bar 16 are pressed against the photosensitive drum 5 by the pressurizing springs 19, 19 through the slide bearings 30, 30 with a predetermined pressure.
  Therefore, due to the urging force of the pressure springs 19, 19, the convex portion forming members 18, 18 on both sides of the charging roller 14 come into contact with the surface of the photosensitive drum 5, respectively, and the convex portion forming members 18, 18 of the elastic roller portion 17. A gap G is formed between the inside portion of the portion where 18 is provided and the surface of the photosensitive drum 5, and the portion is not in contact.
[0034]
  A gear 40 is fixed to one end on the right side of the cored bar 16 of the charging roller 14 in FIG. 3, and a driving gear (not shown) fixed to one end of the photosensitive drum 5 is engaged therewith. Accordingly, when the photosensitive drum 5 is rotated, the gear 40 is rotated by the driving gear, whereby the charging roller 14 is rotated at the same linear velocity as that of the photosensitive drum 5.
  As for the application of the voltage to the charging roller 14, for example, DC-700V is applied to the portion of the core metal 16 by constant voltage control, and an AC voltage is applied by constant current control.
[0035]
  In the charging roller 14, for example, the outer diameter of the cored bar 16 is formed to φ8 mm, and the elastic roller portion 17 is formed in a rubber layer having an outer diameter of φ11 mm made of the above-described epichlorohydrin rubber having a wall pressure of 1.5 mm.
  Furthermore, the elastic roller part 17 uses that whose test piece hardness of rubber itself is 60 degree | times, for example.
[0036]
  Further, the photosensitive drum 5 is rotationally driven in a direction indicated by an arrow C in FIG. 2 by a motor that is rotationally driven via a drum driving timing belt and a drum driving pulley (both not shown).
[0037]
  The developing devices 10A to 10D shown in FIG. 5 have the same configuration, and they differ only in the color of the toner used. The developing device 10A uses yellow toner, the developing device 10B uses magenta toner, the developing device 10C uses cyan toner, and the developing device 10D uses black toner. .
[0038]
  A writing unit 6 shown in FIG. 6 is a laser diode (LD) type color one beam and monochrome two beam, and is a writing unit of one polygon motor having two six-sided rotary polygon mirrors 22a and 22b.
  The writing unit 6 emits yellow scanning light, magenta scanning light, and cyan scanning light by rotating polygon mirrors 22a and 22b emitted from a laser diode (not shown) serving as a light source and rotated by a polygon motor 21. And the black scanning light is reflected separately on the right and left.
[0039]
  The scanning light for yellow and the scanning light for magenta pass through the two-layer fθ lens 23, respectively, and the scanning light for yellow is reflected by the mirror 27, passes through the long WTL 24, and is exposed through the mirrors 28 and 29. Irradiated onto the photosensitive drum 5 of the body unit 2A.
  The magenta scanning light is reflected by the mirror 31, passes through the long WTL 32, and is irradiated onto the photosensitive drum 5 of the photosensitive unit 2B via the mirrors 33 and 34.
[0040]
  Further, the cyan scanning light and the black scanning light pass through the two-layer fθ lens 35, respectively, and the cyan scanning light is reflected by the mirror 36, passes through the long WTL 37, and passes through the mirrors 38 and 39. Irradiated onto the photosensitive drum 5 of the photosensitive unit 2C.
  Further, the scanning light for black is reflected by the mirror 41, passes through the long WTL 42, and is irradiated onto the photosensitive drum 5 of the photosensitive unit 2D via the mirrors 43 and 44.
[0041]
  A duplex unit 7 shown in FIG. 5 includes a pair of conveyance guide plates 45a and 45b and a pair of (four sets in this example) conveyance rollers 46, and forms a duplex image on both sides of a transfer sheet. In the formation mode, an image is formed on one side, conveyed to the reversing conveyance path 54 of the reversing unit 8, and transferred back-switched. The transfer paper P is received, and the image forming unit on which the photosensitive units 2A to 2D are provided. Re-carry toward the part.
[0042]
  The reversing unit 8 includes a plurality of paired transport rollers and a plurality of paired transport guide plates. As described above, the reversing unit 8 reverses the transfer paper P when double-sided image formation is carried out to the double-sided unit 7. The transfer paper P after image formation is discharged out of the machine in the same orientation, or the paper is reversed outside and turned out of the machine.
  Separating sheet feeding units 55 and 56 for separating and feeding the transfer sheets P one by one are provided in the sheet feeding unit in which the sheet feeding cassettes 11 and 12 are provided.
[0043]
  This small printer employs a roller curvature separation method using the transfer belt 3, and four transfer brushes 57 are provided inside the transfer belt 3 in correspondence with the four photosensitive drums 5, respectively. .
[0044]
  In this small printer, when the image forming operation is started, each photosensitive drum 5 rotates in the clockwise direction in FIG. The surface of each photosensitive drum 5 is uniformly charged by applying a voltage between the photosensitive drum 5 and the charging roller 14 of each charging device.
  The charging unit 6 irradiates the charged surface of the photosensitive drum 5 of the photosensitive unit 2A with laser light corresponding to the yellow image.
[0045]
  Further, a laser beam corresponding to a cyan image is written on the charging surface of the photosensitive drum 5 of the photosensitive unit 2B by the writing unit 6, and a magenta image is applied to the charging surface of the photosensitive drum 5 of the photosensitive unit 2C. Further, a laser beam corresponding to a black image is irradiated on the charging surface of the photosensitive drum 5 of the photosensitive unit 2D, and a latent image corresponding to each color is formed thereon.
  Each latent image reaches the position of the developing devices 10A, 10B, 10C, and 10D by the rotation of the photosensitive drum 5, and is developed there by toners of yellow, magenta, cyan, and black, and then is divided into four colors. Toner image.
[0046]
  On the other hand, the transfer paper P is fed from the selected paper feed stage of the paper feed cassette 11 or 12 by the separation paper feed unit 55 or 56, and the pair of registration rollers provided immediately before the photosensitive unit 2A. 59, the toner image is conveyed between the photosensitive drum 5 of the photosensitive unit 2A and the transfer belt 3 at an accurate timing coincident with the toner image formed on each photosensitive drum 5.
[0047]
  At that time, the transfer paper P is charged to a positive polarity by a paper suction roller 58 disposed in the vicinity of the entrance of the transfer belt 3, and thereby electrostatically attracted to the surface of the transfer belt 3.
  Then, while the transfer paper P is attracted to the transfer belt 3 and is conveyed in the same direction by the rotation of the transfer belt 3 in the direction of arrow A, yellow, magenta, cyan, and cyan are transferred to the upper surface in FIG. Each black toner image is sequentially transferred, and when passing through the photoreceptor unit 2D, a full-color toner image of four colors superimposed is formed.
[0048]
  The transfer paper P is heated and pressed by the fixing device 9 to melt and fix the toner image, and then passes through the paper discharge system corresponding to the designated mode, and then the paper discharge tray 26 at the upper part of the apparatus main body. Or the paper is fed straight from the fixing device 9 and passes through the reversing unit 8 and is ejected straight.
[0049]
  Alternatively, when the double-sided image forming mode is selected, the sheet is sent to the reversing conveyance path 54 in the reversing unit 8 described above, then switched back and conveyed to the double-sided unit 7, and is fed again from there to the photosensitive unit. The image forming unit provided with 2A to 2D is discharged after an image is formed on the back surface.
  Thereafter, when two or more image formations are instructed, the above-described image forming process is repeated.
[0050]
  by the way,This photoreceptor unit2A to 2D, both end portions Wc of the cleaning effective width Wc for cleaning the surface of the photosensitive drum 5 by the cleaning blade 47 as shown in FIG.₁, Wc₂However, the convex portion forming members 18, 18 on both sides of the surface of the photosensitive drum 5 are positioned outside the portions where they are in contact with each other.
[0051]
  Specifically, as shown in FIG. 7, the effective charging area Ac, which is a portion between the portions where the convex forming members 18 and 18 on both sides of the charging roller 14 are respectively provided, is set to 308 mm, and each outside thereof. Are provided with convex portion forming members 18 and 18 having a width of 8 mm, and therefore the distance between the outer sides of the convex portion forming members 18 and 18 on both sides thereof is 324 (308 + 8 + 8) mm.
[0052]
  On the other hand, since the cleaning blade width of the cleaning blade 47 which becomes the cleaning effective width Wc is 326 mm, both end portions Wc of the cleaning effective width Wc are set.₁, Wc₂However, they are located on the outer sides of the portions where the convex forming members 18 on both sides of the surface of the photosensitive drum 5 are in contact with each other.
  In addition,This small printerIn this, the maximum transfer width, the maximum image width, the effective writing width, the width of the photosensitive body tube, the effective film thickness, the charging roller width, and the charging roller cleaner width which are the widths of the base constituting the photosensitive drum 5 The dimensions are the lengths shown in FIG. 7 (the length of the charging roller 14 in the axial direction).
[0053]
  Like thisSmall printerThen, both ends Wc of the cleaning effective width Wc for cleaning the surface of the photosensitive drum 5 by the cleaning blade 47.₁, Wc₂However, the convex portion forming members 18, 18 on both sides of the surface of the photosensitive drum 5 are not positioned on the inner side (effective charging area Ac) than the portions in contact with each other.
[0054]
  Incidentally, the photoconductor units 2A to 2D shown in FIG. 1 are provided with side seals 62 and 63 at both ends of the cleaning blade 47 whose one end edge is in sliding contact with the surface of the photoconductor drum 5 as shown in the figure. If transfer residual toner or the like (including some paper dust or dust) is adhered to the surface of the photosensitive drum 5 after the image is transferred, the toner is removed when the cleaning blade 47 scrapes it off and cleans it. Etc. do not leak outside the side seals 62 and 63 on both sides. However, some toner may pass through the cleaning blade 47 and leak, corresponding to the side seals 62 and 63 on both sides.
[0055]
  In this case, the leaked toner reaches a certain position of the charging roller 14 by the rotation of the photosensitive drum 5 and is transferred to the surface of the convex portion forming member 18 as described in FIG. Since the gap G is increased, the charging performance is degraded.
[0056]
  However, thisSmall printerThen, as described with reference to FIG. 1, both end portions Wc of the cleaning effective width Wc.₁, Wc₂However, since the protrusions 18 and 18 on both sides of the surface of the photosensitive drum 5 are positioned outside the portions where they are in contact with each other, the length of the cleaning blade 47 scraped off from the surface of the photosensitive drum 5 is Direction both ends (both ends Wc₁, Wc₂The toners in the vicinity of the same) are restricted by the side seals 62 and 63 on both sides from moving outward.
[0057]
  At this time, even if a part of the toner passes through both end portions of the cleaning blade 47 and reaches the charging roller 14, the toner is located on the outer sides of the convex forming members 18 and 18 on both sides. It does not adhere to the surface of the member 18. Therefore, since the gap G does not change, good charging performance can be obtained.
[0058]
  FIG. 8 shows an image carrier unit provided with a convex cleaning means for cleaning the surface of each convex forming member on both sides of the charging roller.ExampleFIG. 2 is a perspective view showing the vicinity of a charging roller for explaining the above.
  This image carrier unit2 is provided with cleaning brushes 65 and 65, which are convex cleaning means for cleaning the surfaces of the convex forming members 18 and 18 on both sides of the charging roller 14, respectively, with respect to the photosensitive units 2A to 2D described in FIG. Only the points provided are different.
[0059]
  The cleaning brushes 65 and 65 are arranged in a state where the brush tips are respectively inserted into the surfaces of the convex forming members 18 and 18 fixed to both ends of the charging roller 14 by a predetermined amount. Rotation in the direction rotates in the direction indicated by the arrow K to remove dirt such as toner adhering to the surfaces of the convex portion forming members 18 and 18.
  In this way, even if scattered toner or toner floating in the apparatus adheres to the surface of the convex forming member 18, it can be reliably removed by the cleaning brushes 65, 65.
[0060]
  FIG. 9 is provided with a long cleaning brush that simultaneously cleans the entire convexity forming member on both sides and the entire charging effective area of the charging roller.According to this inventionFIG. 9 is a perspective view showing the vicinity of a charging roller in order to describe an embodiment of the photosensitive unit, and the same reference numerals are given to portions corresponding to those in FIG. 8.
  The photoconductor unit according to this embodiment is shown in FIG.Example shown inOn the other hand, a long cleaning brush 70 as a means for simultaneously cleaning the entire charging effective area Ac of the charging roller is used, and the surface of the convex forming members 18 and 18 on both sides and the charging effective area Ac of the charging roller 14 are The whole area is cleaned at the same time.
[0061]
  In this way, the gap G described with reference to FIG. 3 can be prevented from changing due to adhering substances such as toner adhering to the surface of the convex portion forming member 18, and the charging roller 14 can be prevented from changing. Even if the charging effective area Ac is contaminated by scattered toner or floating toner in the apparatus, it can be reliably removed.
[0062]
  FIG. 10 shows an example of a photoconductor unit in which convex portion forming members for forming the respective convex portions are formed continuously over the entire circumference in the circumferential direction and have no stepped portion due to a seam in the middle. It is a perspective view which shows the charging roller vicinity in order to demonstrate a form.
  The photoreceptor unit according to this embodiment is different from the photoreceptor units 2A to 2D described in FIG. 2 in that the shape of the convex forming members 68 and 68 on both sides is different from that of the elongated unit described in FIG. The only difference is that the cleaning brush 70 is provided.
[0063]
  And the convex part formation members 68 and 68 of both sides are made not to make the level | step-difference part by a seam in the middle by making it continue over the perimeter of the circumferential direction, for example by using a heat shrinkable tube of 8 mm width. Yes.
  Even in this case, as in the embodiment described with reference to FIG. 9, it is possible to prevent the change in the gap G (see FIG. 3) caused by the adhering matter such as toner adhering to the surface of the convex forming member 68. Can do. Further, even if the effective charging area Ac of the charging roller 14 'is contaminated by scattered toner or floating toner in the apparatus, it can be removed immediately.
[0064]
  FIG. 11 is a perspective view showing the vicinity of the charging roller in order to explain an embodiment of the photoreceptor unit provided with a long convex cleaning means made of sponge.
  The photosensitive unit according to this embodiment is different from the photosensitive unit according to the embodiment described with reference to FIG. 10 in that the convex cleaning means is a long convex cleaning member 80 made of sponge, and the convex cleaning member 80 is The surfaces of the convex forming members 68 on both sides and the entire charging roller 14 'charging effective area Ac are simultaneously cleaned.
[0065]
  In this way, as in the embodiment described with reference to FIG. 10, it is possible to prevent the gap G described with reference to FIG. Even if the effective charging area Ac is contaminated by scattered toner or floating toner in the apparatus, it can be removed.
[0066]
【The invention's effect】
  As described above, the present inventionImage carrier unit andAccording to the image forming apparatus, both ends of the cleaning effective width of the cleaning device for cleaning the surface of the image carrier are more than the portions where the convex portions at both ends of the charging roller are in contact with the surface of the image carrier. Since the toner is not located inside, even if the toner leaks at both ends of the cleaning effective width, the toner does not adhere to the portion corresponding to the area between the convex portions at both ends of the charging roller.
  Therefore, since the toner does not adhere to the portion that affects the charging performance of the charging roller, good charging performance can be obtained.
[0067]
  Also,Surface of each convex part on both sides of charging rollerCleanSince the convex cleaning means is provided, the surface of each convex portion can be forcibly cleaned, so that the gap can be made more stable.
  Further, since the convex cleaning means simultaneously cleans the entire charging effective area of the charging roller, more stable charging performance can be obtained.
[0068]
  In addition, each of the above convex portionsIt is continuous over the entire circumference in the circumferential direction and does not have a step due to the seam in the middle.If it is in shape,Even when the convex portion is formed by sticking a tape material or the like to the charging roller, the convex portion can be prevented from being peeled off during cleaning by the convex portion cleaning means.
[Brief description of the drawings]
FIG. 1 This inventionThe basis ofFIG. 5 is a schematic diagram for explaining an effective cleaning width of a cleaning device provided in a photoconductor unit that is an image carrier unit.
FIG. 2 is a configuration diagram showing the photosensitive unit.
FIG. 3 is a schematic view showing a part of a charging device and a photosensitive drum that are also provided in the photosensitive unit.
FIG. 4 is a front view showing only one end side of the charging roller in order to explain a joint portion of the convex forming member wound around both ends of the charging roller.
FIG. 5 is an overall configuration diagram showing a small color printer that is an image forming apparatus including a plurality of the photoreceptor units of FIG. 2;
FIG. 6 is a block diagram showing a writing unit similarly provided in the small printer.
7 is a schematic diagram for comparing width dimensions of portions related to image formation of the small printer of FIG. 5; FIG.
FIG. 8 shows an image carrier unit provided with a convex cleaning means for cleaning the surface of each convex forming member on both sides of the charging roller.ExampleFIG. 2 is a perspective view showing the vicinity of a charging roller for explaining the above.
FIG. 9 is provided with a long cleaning brush that simultaneously cleans the entire area of the charging effective area of the convex roller forming member and the charging roller.According to this inventionFIG. 3 is a perspective view showing the vicinity of a charging roller in order to explain an embodiment of the photosensitive unit.
FIG. 10 is a schematic diagram of a photoconductor unit in which convex portion forming members for forming each convex portion are formed continuously over the entire circumference in the circumferential direction and do not have a step portion due to a seam in the middle. FIG. 3 is a perspective view showing the vicinity of a charging roller for explaining an embodiment.
FIG. 11 is a perspective view showing the vicinity of a charging roller in order to explain an embodiment of a photoconductor unit provided with a long convex cleaning means made of sponge.
FIG. 12 is a perspective view for explaining an entrance seal and a side seal.
FIG. 13 is a schematic diagram for explaining a point in which inconvenience occurs when both ends of the cleaning effective width of the cleaning blade for cleaning the surface of the photosensitive drum are positioned inside the convex portion forming member.
[Explanation of symbols]
2A, 2B, 2C, 2D: Photosensitive unit (image carrier unit)
4: Charging device 5: Photosensitive drum (image carrier)
14, 14 ': Charging roller
18, 68: Projection forming member
47: Cleaning blade
65, 70: Cleaning brush (convex part cleaning means)
80: Convex cleaning member (convex cleaning means)

Claims (3)

A charging roller, and the image bearing member, the both end portions along with its and a cleaning device for cleaning the surface of the image carrier, formed by each predetermined width protrusions at both ends over a circumferential direction of the charging roller Are formed in contact with the surface of the image carrier to form a gap between the inside of the convex portions on both sides of the charging roller and the surface of the image carrier. In the image carrier unit for charging the surface of the image carrier to a predetermined potential by discharging in the gap between the image carrier and the image carrier,
The cleaning device is arranged such that both end portions of the effective cleaning width for cleaning the surface of the image carrier are not located inside the portions where the convex portions on both sides of the surface of the image carrier are in contact with each other. An image carrier unit comprising: a convex portion cleaning means for simultaneously cleaning the surface of each convex portion on both sides of the charging roller and the entire charging effective area of the charging roller . Wherein each of the convex portions, wherein, characterized in that in the shape having no stepped portion by seams in the middle have been formed at both ends a circumferential direction of the entire circumference continuously the charging roller Item 2. The image carrier unit according to Item 1 . An image forming apparatus including an image carrier unit according to claim 1 or 2, wherein.

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