JP2014048580A - Developing gap holding mechanism, and developing device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing gap holding mechanism capable of securing a developing gap set between a photoreceptor drum and a developing roller in an accurate and stable manner.SOLUTION: A developing gap holding mechanism includes flange bodies 17 each having a circular projected part 18, a developing roller 7, and gap securing rollers 28 provided on both outer end parts in the axial direction of the developing roller 7. The outer diameter D1 of the circular projected part 18 is made smaller than the outer diameter D2 of a photoreceptor drum 1, and a step part 32 is provided between a photosensitive surface of the photoreceptor drum 1 and an outer peripheral surface 31 of the circular projected part 18, so that foreign substances attached to the photosensitive surface of the photoreceptor drum 1 are dropped from the step part 32 to the outer peripheral surface 31 of the circular projected part 18, and scraped off by a cleaning brush 12.

Description

  The present invention relates to an electrophotographic image forming apparatus using a photosensitive drum and a developing roller, and in particular, to ensure a developing gap set between the photosensitive drum and the developing roller with high accuracy and stability. The present invention relates to a development gap holding mechanism.

  In an image forming apparatus such as an electrophotographic printer, MFP (Multifunction Peripherals), or production printing, if the developing gap (Pg) between the photosensitive drum and the developing roller cannot be maintained constant, There is a problem that unevenness occurs and the image quality deteriorates. Conventionally, there is a proposal described in Japanese Patent Application Laid-Open No. 2007-71925 (Patent Document 1) in order to keep the development gap (Pg) constant with a simple structure.

FIG. 16 is a front view showing a joining state of the photosensitive drum and the developing roller according to this proposal.
As shown in the figure, cylindrical flange bodies 101 </ b> A and 101 </ b> B having the same outer diameter as the photosensitive drum 100 are provided at both ends of the photosensitive drum 100. On the other hand, the developing roller 103 is arranged in parallel to the photosensitive drum 100, and both ends of the developing roller 103 are formed in a cylindrical shape in contact with the flanges 101A and 101B of the photosensitive drum 100, respectively. Contact roller bodies 103A and 103B are provided.

  The outer diameters of the contact roller bodies 103A and 103B are designed to be larger than the outer diameter of the developing roller 103, and the flange bodies 101A and 101B of the photosensitive drum 100 and the contact roller bodies 103A and 103B of the developing roller 103 contact each other. As a result, a developing gap Pg is formed between the photosensitive drum 100 and the developing roller 103.

  Further, a spiral groove 104 is formed along the circumferential direction in the flange bodies 101A and 101B, and a spiral groove 105 is formed along the circumferential direction in the contact roller bodies 103A and 103B. When foreign matter such as toner powder adheres to the flanges 101A and 101B or the contact roller bodies 103A and 103B, the foreign matter can escape into the grooves 104 and 105, thereby preventing the development gap Pg from fluctuating due to the presence of foreign matter. The structure is as follows.

  In addition, as prior art for maintaining a constant development gap between the photosensitive drum and the developing roller, for example, Japanese Patent Laid-Open No. 05-119602 (Patent Document 2) and Japanese Patent No. 3064576 (Patent Document 3). JP-A-2000-010316 (Patent Document 4) and the like can also be mentioned.

  However, in the conventional developing gap holding mechanism shown in FIG. 16, since the outer diameter of the flange body 101 is the same as the outer diameter of the photosensitive drum 100, residual toner or the like adhering to the photosensitive surface of the photosensitive drum 100 is removed. For example, even if the foreign material is pushed to the flange body 101 side with a blade member and is allowed to escape to the groove 104, there is resistance, and the foreign body is caught between the flange body 101 and the abutting roller body 103 without resistance. There is a problem that the development gap Pg varies.

  Further, since the outer diameter of the flange body 101 is the same as the outer diameter of the photosensitive drum 100, the foreign matter easily returns to the photosensitive surface side of the photosensitive drum 100 again before reaching the groove 104, and the photosensitive body. On the outer peripheral surfaces of the drum 100 and the flange body 101, the amount of foreign matter increases with time, which eventually causes fluctuations in the development gap Pg.

  An object of the present invention is to provide a developing gap holding mechanism that can secure a developing gap set between a photosensitive drum and a developing roller with high accuracy and stability.

In order to achieve the above object, the present invention provides:
A cylindrical photosensitive drum;
A drum blade member in contact with the photosensitive surface of the photosensitive drum;
A flange body provided at each end opening of the photosensitive drum and having a circular convex portion protruding outward in the axial direction of the photosensitive drum;
A developing roller arranged in parallel with the photosensitive drum;
Gap ensuring rollers provided at both axially outer ends of the developing roller,
In the development gap holding mechanism in which the outer peripheral surface of the gap ensuring roller is in contact with the outer peripheral surface of the circular convex portion,
The outer diameter D1 of the circular convex portion is smaller than the outer diameter D2 of the photosensitive drum,
A cleaning member in contact with the outer peripheral surface of the circular convex portion is provided.

  In the present invention, as described above, the stepped portion is provided between the photosensitive surface of the photosensitive drum and the outer peripheral surface of the circular convex portion by making the outer diameter D1 of the circular convex portion smaller than the outer diameter D2 of the photosensitive drum. The foreign matter adhering to the photosensitive surface of the photosensitive drum is scraped by the drum blade member and can be easily dropped from the stepped portion onto the outer peripheral surface of the circular convex portion. The dropped foreign matter does not return to the photosensitive surface side of the photosensitive drum again.

  Therefore, it is possible to provide a development gap holding mechanism that can reliably secure a development gap set between the photosensitive drum and the development roller with high accuracy and reliably eliminate foreign matters.

FIG. 3 is a schematic front view of a part for explaining the photosensitive drum unit according to the first embodiment of the present invention. FIG. 6 is a side view showing a state in which a developing gap between the photosensitive drum and the developing roller is formed and secured by contact between the circular convex portion and the gap ensuring roller in this embodiment. It is a partial cross section figure on the FIG. 2A-A line. It is a side view of the circular convex part which concerns on 2nd Example of this invention. It is an expanded sectional view on a 4B-B line. It is a side view of the circular convex part which concerns on 3rd Example of this invention. It is a side view for demonstrating 4th Example of this invention, The figure (a) is the state which opened the cover member, The figure (b) is a figure which shows the state which closed the cover member. It is a side view for demonstrating 5th Example of this invention, and is a figure which shows the state which closed the cover member. It is a top view which shows the contact state of the circular convex part and gap ensuring roller for demonstrating 6th Example of this invention. It is an expanded sectional view of the contact part of the circular convex part and a gap ensuring roller. It is a top view which shows the contact state of the circular convex part and gap ensuring roller for demonstrating 7th Example of this invention. It is a schematic front view of the photosensitive drum unit for explaining the eighth embodiment of the present invention. It is a schematic front view of the photosensitive drum unit for explaining the ninth embodiment of the present invention. It is a schematic front view of the photosensitive drum unit for explaining the tenth embodiment of the present invention. 1 is a schematic configuration diagram around a photosensitive drum in an electrophotographic image forming apparatus according to an embodiment of the present invention. It is a front view which shows the joining state of the photosensitive drum and the developing roller in the conventionally proposed image forming apparatus.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 15 is a schematic configuration diagram of the periphery of a photosensitive drum in an electrophotographic image forming apparatus according to all the embodiments of the present invention.

  As shown in the figure, around the photosensitive drum 1, a charging roller 2, an optical writing means 3, a developing unit 4, a transfer unit 5, a cleaning unit 6 and the like are arranged along the rotation direction thereof. Yes.

  The developing unit 4 includes a developing roller 7 disposed so as to face the photosensitive drum 1, a toner supply roller 8 that supplies toner (not shown) to the developing roller 7, and a stirring roller 9 that stirs the toner. I have. The cleaning unit 6 includes a drum blade member 10 that is in sliding contact with the outer peripheral photosensitive surface of the photosensitive drum 1, a drum cleaning brush 11 that is provided downstream of the drum blade member 10 in the rotational direction of the photosensitive drum, and the like. It has.

  Based on a printing operation start signal from a controller (not shown) of the image forming apparatus, the photosensitive drum 1 starts to rotate in the arrow direction. The photosensitive drum 1 rotates at a speed corresponding to the printing speed of the image forming apparatus and continues to rotate until the printing operation is completed. When the photosensitive drum 1 starts rotating, a high voltage is applied to the charging roller 2 and the photosensitive surface of the photosensitive drum 1 is uniformly charged.

  When character data or graphic data converted into a dot image is sent from the controller to the image forming apparatus as a laser beam on / off signal, the light writing means 3 irradiates the photosensitive surface of the photosensitive drum 1 with the laser beam. A part and a non-irradiated part, a so-called electrostatic latent image is formed.

  When the area of the photosensitive drum holding the electrostatic latent image arrives at a position facing the developing roller 7, toner is supplied to the electrostatic latent image to form a toner image.

  The paper P stored in the paper hopper (not shown) is synchronized with the timing at which the toner image formed on the photosensitive drum 1 arrives at the transfer position by the paper transport means (not shown). It is conveyed between the body drum 1 and the transfer unit 5. The toner image formed on the photosensitive drum 1 is sucked onto the paper P by the action of the transfer device 5 that applies a charge having a polarity opposite to that of the toner image to the back side of the paper P.

  The paper P onto which the toner image has been transferred in this manner is conveyed to a fixing device (not shown), and is nipped and conveyed while being heated and pressurized by the nip portion between the heating roller and the pressure roller, so that the toner image is fused and fixed on the paper P. The After the fixing, the paper P is discharged out of the apparatus and stocked by a paper conveying means (not shown).

Next, specific examples of the development gap holding mechanism will be described.
(First embodiment)
FIG. 1 is a partially exploded schematic front view for explaining the photosensitive drum unit according to the first embodiment of the present invention.
As shown in FIG. 1, a flange body 15 is fitted into both end openings of the cylindrical photosensitive drum 1. The photosensitive drum 1 is made of a drum-like tube by a method such as extrusion or drawing with a material such as an aluminum alloy, and then the photosensitive drum 1 is finished through processes such as cutting, finishing, and polishing. The processing standard at this time is the fitting portion 19 with the flange body 15.

  Whether the flange body 15 is cut by a lathe or injection-molded, concentric machining can provide high accuracy with a flare accuracy on the order of several microns. In the case of using a metal material, aluminum or an aluminum alloy is optimal in terms of mechanical strength and weight. On the other hand, when a synthetic resin is used, a polyimide resin or the like is preferable in consideration of strength and a thermal expansion coefficient.

  A flange portion 16 and a fitting portion 17 are provided on the inner side of the flange body 15 facing the opening portion of the photosensitive drum, and projecting outward in the axial direction from the flange portion 16 on the opposite side to the opening portion of the photosensitive drum 1. The circular convex portion 18 is provided. The flange portion 16, the fitting portion 17, and the circular convex portion 18 are formed concentrically, and the circular convex portion 18 is for pressing a gap roller as will be described later.

  A central hole 20 is provided through the center of the flange body 15, and the drum rotation shaft 21 is inserted through the central hole 20. The center hole 20 (drum rotating shaft 21) serves as a rotation reference. Further, the photosensitive drum 1 is provided with a fitting portion 19 with the flange body 15 on the inner side of the opening portions on both sides by a separate process, which serves as a rotation reference for the photosensitive drum 1.

  The photosensitive drum 1 and the flange body 15 are connected by fitting the fitting portion 17 of the flange body 15 into the opening of the photosensitive drum 1 and inserting the drum fixing pin 22 in the direction of the arrow. Further, as shown in FIG. 2, a transmission pin insertion hole 23 is formed in the drum rotating shaft 21 so as to penetrate in the diameter direction. By inserting the rotation transmission pin 24 into the transmission pin insertion hole 23, The rotational driving force of the drum rotation shaft 21 is transmitted to the flange body 15 through the rotation transmission pin 24.

  Further, a pin retaining collar 25 and a bearing 26 are attached to the drum rotating shaft 21, and a drum driving gear 27 is connected to one end of the drum rotating shaft 21.

  As shown in FIG. 2, the outer periphery of the circular convex portion 18 of the flange body 15 is in the vicinity of the fitting portion 19 of the photosensitive drum 1 and slightly in the direction of the center hole 20, as shown in FIG. In contact with the gap ensuring roller 28 on the developing roller 7 side, the formation of a developing gap (Pg) between the photosensitive drum 1 and the developing roller 7 is ensured.

  Therefore, one side (the flange portion 16 and the fitting portion 17) of the flange body 15 functions as a support for the photosensitive drum 1, and the other side (circular convex portion 18) of the flange body 15 abuts against the gap ensuring roller 28. It functions as a member. In this form, the effect of the rotational moment is small in strength and there is no deformation, so that it can be supported with high accuracy.

  As shown in FIG. 2, the developing roller 7 side is coaxially supported with the developing roller rotating shaft 29 serving as the rotation center thereof, and is supported rotatably by fitting a gap ensuring roller 28 concentrically machined with high accuracy. By pressing the gap ensuring roller 28 against the circular convex portion 18 of the flange body 15, it is possible to rotate with the fluctuation of the developing gap (Pg) between the photosensitive drum 1 and the developing roller 7 kept to a minimum.

  Reference numeral 30 in FIG. 1 indicates a pressing position of the gap ensuring roller 28 on the peripheral surface of the circular convex portion 18. Although not shown, the gap ensuring roller pressing position 30 is also on the circular protrusion 18 on the right side as viewed in FIG. As is apparent from the display of the gap ensuring roller pressing position 30, the axial width W1 of the circular convex portion 18 is designed to be equal to or larger than the axial width W2 of the gap ensuring roller 28 (W1 ≧ W2).

  Further, since the pressure is pressed against the circular convex portion 18 at a position very close to the developing width region, the U-shaped deflection of the drum rotation shaft 21 itself can be minimized, thereby (based on deformation due to axial reaction force). The occurrence of concentration distribution can also be suppressed.

FIG. 3 is a partial cross-sectional view taken along line 2A-A in FIG.
As shown in FIG. 3, the outer diameter D1 of the circular protrusion 18 is slightly smaller than the outer diameter D2 of the photosensitive drum 1 (D1 <D2). The drum side blade member 10 is disposed in parallel with the drum rotation shaft 21, but the lateral width L1 of the drum side blade member 10 in the longitudinal direction is slightly longer than the lateral width L2 of the photosensitive drum 1 in the axial direction. (L1> L2) In the case of the present embodiment, the dimensional relationship is such that the outer peripheral surface 31 of the circular convex portion 18 is covered by both end portions of the drum-side blade member 10.

  As described above, by taking the relationship of (D1 <D2), the stepped portion 32 in which the outer peripheral surface 31 of the circular convex portion 18 is one step lower than the outer peripheral photosensitive surface of the photosensitive drum 1 is replaced with the photosensitive drum 1 and the circular convex portion. It can be formed over the entire circumference of the portion 18. The step portion 32 is directly adjacent to the outer end portion in the axial direction of the outer peripheral photosensitive surface of the photosensitive drum 1. Further, by taking the relationship of (L1> L2), the extended portion 10a of the drum blade member 10 from the photosensitive drum 1, the outer peripheral side end face of the photosensitive drum 1, and the circular protrusion are provided at the stepped portion 32. The outer peripheral surface 31 of the portion 18 forms a foreign substance escape recess 32a that opens outward in the axial direction of the photosensitive drum 1.

  As shown in FIG. 2, a circular convex cleaning brush 12 is provided on the downstream side of the drum-side blade member 10 in the photosensitive drum rotation direction so as to be in sliding contact with the outer peripheral surface 31 of the circular convex 18. Further, a gap ensuring roller blade member 13 slidably contacting the outer peripheral surface of the gap ensuring roller 28, and a gap ensuring roller cleaning brush 14 is provided upstream of the gap ensuring roller rotation direction.

  As described above, since the step portion 32 (foreign material escape recess 32a) is located adjacent to the outer peripheral photosensitive surface of the photosensitive drum 1, foreign matter such as residual toner adhering to the outer peripheral photosensitive surface of the photosensitive drum 1 is obtained. When the drum 33 (see FIG. 3) is scraped by the drum blade member 10, it can easily move to the stepped portion 32 (foreign material escape recess 32a).

  The foreign matter 33 falls from the step portion 32 onto the outer peripheral surface 31 of the circular convex portion 18, and the foreign matter 33 on the outer peripheral surface 31 reaches the contact position with the gap ensuring roller 28 before the circular convex cleaning brush 12. Is eliminated.

  In order to prevent the foreign matter 33 moved to the stepped portion 32 side from returning to the photosensitive surface side of the photosensitive drum 1 again, the stepped portion 32 needs to have a predetermined dimension (for example, about 0.2 mm or more).

In the case of this embodiment, the blade member 13 and the cleaning brush 14 are also provided on the gap ensuring roller 28 side, and the outer peripheral surface of the gap ensuring roller 28 is also cleaned.
For this reason, the foreign matter 33 is interposed between the circular convex portion 18 and the gap ensuring roller 28 so that the development gap Pg does not fluctuate, and the development gap Pg can always be maintained appropriately.

  Since the blade member 10 can be extended with a degree of freedom in the lateral width direction (L1 direction shown in FIG. 3), the circular protrusion 18 generated when the diameter of the flange body 15 (see FIG. 1) is large, The foreign matter 33 can be moved to the stepped portion 32 (foreign matter escaping concave portion 32a) without receiving the problem that the movement becomes difficult and the shape restriction of the blade member 10.

  Further, since both end portions of the blade member 10 also serve as means for guiding / moving the foreign matter 33 toward the stepped portion 32 (foreign matter escape recess 32a), it is not necessary to provide special foreign matter guide / moving means.

  Of course, when the blade member 10 is configured to move the foreign matter 33 to both end portions in the axial direction of the photosensitive drum 1 (for example, the blade member 10 is wedge-shaped with respect to the photosensitive drum 1 and the surface of the photosensitive drum 1). The present invention can also be applied to the case of touching the head.

(Second embodiment)
The fine toner powder having a particle size of several micrometers is scattered and floating in the apparatus innumerably, such as those adhered to the periphery of the photosensitive drum 1 and those scattered from the developing unit 4. There is a concern that the developing gap Pg may fluctuate due to being attached to the circular convex portion 18 and then being compressed by the contact portion with the gap ensuring roller 28.

  FIG. 4 is a side view of a circular convex portion 18 according to the second embodiment of the present invention, and FIG. 5 is an enlarged cross-sectional view along the line BB in FIG. FIG.

  In the case of the present embodiment, a coating film 34 of a fluorine resin such as polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer or the like is formed on the surface of the circular convex portion 18. At the time of injection molding of the flange body 15, minus coating corresponding to the coating thickness of the coating film 34 is performed, and then the coating film 34 is formed by a technique such as dipping a fluororesin. In order to prevent the coating material from concentrating on the end of the circular convex portion 18 and rising, a chamfer (inclined portion) 35 is provided in advance at the peripheral end portion of the circular convex portion 18 as shown in FIG.

  In this embodiment, the chamfer (inclined portion) 35 is provided, but it is also possible to provide roundness instead of the chamfer (inclined portion) 35. Regarding the coating, for example, http: // www. nipponfusso. com / information / lecture. A method for forming a film is described in html, and it is also possible to form a film 34 of a fluororesin on the surface of the circular convex portion 18 by adopting these methods.

(Third embodiment)
FIG. 6 is a side view of the circular protrusion 18 according to the third embodiment of the present invention. In the case of the present embodiment, the circular convex portion 18 includes an inner layer molding portion 36 having a substantially disk-like side surface shape and an outer layer molding portion 37 having a substantially annular side surface so as to cover the outer periphery of the inner layer molding portion 36. Has been. The inner layer molding portion 36 is molded from a general synthetic resin such as polyimide resin, and the outer layer molding portion 37 is molded from a fluorine-based resin.

  The inner layer forming part 36 and the outer layer forming part 37 can be simultaneously formed by a double injection method. Alternatively, the inner layer molding portion 36 and the outer layer molding portion 37 may be separately molded, and the inner layer molding portion 36 may be press-fitted into the hollow portion of the outer layer molding portion 37 to form the circular convex portion 18.

  Regardless of which method is used, an uneven rotation-preventing portion 38 is provided at the joint between the inner layer molding portion 36 and the outer layer molding portion 37 so that loosening and slippage in the rotational direction do not occur. Further, in order to ensure concentric accuracy, when the flutter accuracy cannot be suppressed to a few micrometers, the lathe machining is performed on the basis of the center hole 20 of the flange body 15 so that the accuracy is within a predetermined range. I do.

  Further, as in the second embodiment, a film made of a fluorine resin is formed on the peripheral surface of the gap ensuring roller 28, or a fluorine resin is formed on the outer peripheral portion as in the third embodiment. It is preferable to use a gap ensuring roller 28 that is formed by the above-described method and has an outer layer forming portion.

  If the outer peripheral surface of the circular convex portion 18 and / or the gap ensuring roller 28 is made of a fluorine resin, the toner is applied to the circular convex portion 18 and / or the gap ensuring roller 28 due to the excellent release property of the fluorine resin. Adhesion is greatly reduced, and the development gap Pg can be accurately maintained over a long period of time.

  Since the gap ensuring roller 28 is pressed against the circular convex portion 18 of the flange body 15 and driven to rotate, it is necessary to reduce the frictional resistance during rotation as much as possible. Therefore, a bearing portion such as a ball bearing is provided on the inner peripheral portion of the gap ensuring roller 28, and the outer peripheral portion of the bearing portion is molded with a fluorine resin and the outer layer molded portion is press-fitted, or the outer periphery of the bearing portion is made of a fluorine resin. A film is formed.

  Although not shown, when using the gap ensuring roller 28 configured by an inner layer molding portion having a substantially circular side shape and an outer layer molding portion having a substantially annular side surface so as to cover the outer periphery of the inner layer molding portion, The inner layer molding portion serves as a bearing portion. In this structure, no detent portion is provided between the inner layer molded portion and the outer layer molded portion. Moreover, you may shape | mold both the inner layer shaping | molding part and an outer layer shaping | molding part with the fluorine resin excellent in slipperiness.

(Fourth embodiment)
7A and 7B are side views for explaining the fourth embodiment of the present invention. FIG. 7A shows a state in which the cover member is opened, and FIG. 7B shows a state in which the cover member is closed.

  In the present embodiment, in order to further prevent the toner powder from entering, the circular convex portion 18 side is covered with a circular convex portion cover member 39, while the gap ensuring roller 28 side is covered with a gap ensuring roller cover member 40. It has been broken. Thus, in this embodiment, the photosensitive drum side and the developing roller side are divided and covered by the cover members 39 and 40.

  With respect to the fixed circular convex cover member 39, the gap ensuring roller cover member 40 can be rotated by a predetermined angle around a rotation fulcrum 41.

  As shown in FIG. 7A, openings are provided in the vicinity of the contact portion between the circular convex portion 18 and the gap ensuring roller 28 of the circular convex portion cover member 39 and the gap ensuring roller cover member 40, respectively. A cover sealing member 42 for sealing the mating portions of the cover members 39 and 40 is adhered to the outside of the opening portions of the circular convex cover member 39 and the gap security roller cover member 40, respectively.

The circular convex cover member 39 rotates around the drum rotating shaft 21 and the rotating shaft seal member 43 rotates around the developing roller rotating shaft 29 around the gap security roller cover member 40. A shaft seal member 43 is adhered to each other.
As the seal members 42 and 43, for example, an elastic body such as low foam rubber, low foam synthetic resin, felt, or non-woven fabric is used. In FIG. 7, reference numeral 44 denotes a drum-side opening provided on the side surface of the circular convex cover member 39.

(5th Example)
FIG. 8 is a diagram for explaining a fifth embodiment of the present invention.
According to the fourth embodiment, toner powder can be largely prevented from entering the contact portion between the circular convex portion 18 and the gap ensuring roller 28. However, there is still a concern that the toner powder may intrude during a component attaching / detaching operation such as maintenance of the image forming apparatus. is there.

  In the present embodiment, on the basis of the fourth embodiment, a drum blade member 10, a circular convex cleaning brush 12, and a circular convex double-sided adhesive tape 45 are further installed in the circular convex cover member 39. On the other hand, the gap ensuring roller blade member 13, the gap ensuring roller cleaning brush 14, and the gap ensuring roller double-sided adhesive tape 46 are installed in the gap ensuring roller cover member 40.

  As shown in FIG. 8, the double-sided adhesive tapes 45 and 46 are attached to the inner bottom surfaces of the cover members 39 and 40, and preferably are attached near the blade members 10 and 13 and the cleaning brushes 12 and 14. Has been.

  In this embodiment, even if a small amount of toner powder enters, the blade members 10 and 13 are installed and scraped so that the toner powder does not bite into the contact portion between the circular convex portion 18 and the gap ensuring roller 28. Further, the cleaning brushes 12 and 14 are installed to clean the circular convex portion 18 and the gap ensuring roller 28.

  The collected toner powder is fixed by adhesive with the double-sided adhesive tapes 45 and 46 so that the toner powder does not rise when the cover members 39 and 40 are opened.

  In order to continuously and stably clean toner powder having a particle size of several micrometers, it is necessary to maintain contact between the blade members 10 and 13 with high accuracy. However, when the blade members 10 and 13 are used for a long period of time, the friction durability deteriorates, and toner slips out due to deformation or wear of the contact portions of the blade members 10 and 13. Installation of the cleaning brushes 12 and 14 is effective to eliminate the toner slipping.

  In this embodiment, as shown in FIG. 8, in order to effectively drop and remove foreign matters such as toner powder, the blade member 10 and the cleaning brush 12 are located below the photosensitive drum 1 in the gravity direction, preferably the photosensitive drum. 1, the blade member 13 and the cleaning brush 14 are installed below the gap ensuring roller 28 in the direction of gravity, preferably near the lower end. The cleaning brushes 12 and 14 are installed on the upstream side of the blade members 10 and 13 in the rotation directions of the photosensitive drum 1 and the gap ensuring roller 28, respectively.

(Sixth embodiment)
FIG. 9 is a view for explaining a sixth embodiment of the present invention, and FIG. 10 is an enlarged cross-sectional view of a contact portion between the circular convex portion 18 and the gap ensuring roller 28.

  Due to the importance of managing the development gap Pg, it is necessary to take measures more strictly without the presence of toner powder. In the case of the present embodiment, a plurality of annular grooves 47 extending in the direction perpendicular to the axial direction of the drum rotating shaft 21 are formed at a constant depth on the outer peripheral portion of the circular convex portion 18.

  As shown in FIG. 10, the bottom of the annular groove 47 has a substantially U-shaped cross section, and the opening edge of the annular groove 47 is provided with an inclined or rounded chamfer 48. The toner powder dammed up by the blade member 10 and the cleaning brush 12 along with the rotation of the flange body 15 (circular convex portion 18) is once accommodated in the annular groove 47 and then falls together from the circular convex portion 18.

  The bottom of the annular groove 47 has a substantially U-shaped cross section so that the toner powder can easily move and drop into the annular groove 47, and the opening edge of the annular groove 47 is inclined or A rounded chamfer 48 is provided. When the annular groove is formed by edge processing, toner powder may be caught due to the occurrence of burrs or the like, and may be stagnated in the annular groove. On the other hand, if the bottom of the annular groove 47 is U-shaped in cross section and the chamfer 48 is applied to the opening edge of the annular groove 47 as in this embodiment, the toner powder can be smoothly moved without being caught. The toner powder is surely eliminated.

  In the present embodiment, the annular groove 47 is formed only in the circular convex portion 18, but the same effect can be obtained by forming the annular groove 47 in the gap ensuring roller 28.

(Seventh embodiment)
FIG. 11 is a diagram for explaining a seventh embodiment of the present invention.
The contact width between the circular protrusion 18 and the gap ensuring roller 28 is at most about 5 mm. If a plurality of annular grooves 47 are provided on the circular convex portion 18 and the gap ensuring roller 28 to face each other, the allowable value of the position becomes 1 mm or less depending on the stacking of the assembly intersections (for example, the circular convex portion 18). ) Of the other (for example, the gap ensuring roller 28) may be meshed with a protruding portion that does not form the annular groove 47. If so, there arises a disadvantage that the development gap Pg cannot be properly secured.

  Therefore, in this embodiment, as shown in FIG. 11, the spiral groove 49a having a constant lead angle (twist angle) is formed in the circular convex portion 18, while the spiral groove 49a has a lead angle on the gap ensuring roller 28. The spiral grooves 49b having different (twist angles) were formed to rotate both in contact. By doing so, the inconveniences described above are eliminated, and assembly with a sufficient margin becomes possible.

  The toner powder that has entered the spiral groove 49 a of the circular protrusion 18 is scraped by the cleaning brush 12, and the toner powder that has entered the spiral groove 49 b of the gap ensuring roller 28 is scraped by the cleaning brush 14.

  Similarly to the sixth embodiment, the spiral grooves 49a and 49b are preferably formed so that the cross-sectional shape of the groove bottom is substantially U-shaped, and the groove opening edge is chamfered with an inclination or roundness.

  If the groove processing described in FIGS. 9 to 11 and the use of the fluororesin described in FIGS. 4 to 6 are used in combination, it is possible to reliably prevent foreign matters such as toner powder from remaining and being fixed. As a result, the cleaning effect is further enhanced, and the development gap is accurately secured over a long period of time.

(Eighth embodiment)
FIG. 12 is a schematic front view of a photosensitive drum unit for explaining an eighth embodiment of the present invention.
In the first embodiment shown in FIG. 3, the outer peripheral surface 31 of the circular convex portion 18 is almost completely covered by both end portions (extension portions 10a) of the drum blade member 10, but in this embodiment, The lateral width L1 of the drum side blade member 10 is slightly longer than the lateral width L2 of the photosensitive drum 1. As a result, the toner powder scraped by the drum side blade member 10 does not fly out and easily moves to the outer peripheral surface 31 of the circular convex portion 18.

(Ninth embodiment)
FIG. 13 is a schematic front view of a photosensitive drum unit for explaining a ninth embodiment of the present invention.
In the case of the present embodiment, the protrusion preventing flange portion 50 of the protrusion having an outer diameter D3 larger than the outer diameter D1 of the circular convex portion 18 on the outer side in the axial direction of the circular convex portion 18 is concentric with the circular convex portion 18. Is provided. In this embodiment, as shown in FIG. 13, the outer diameter D1 of the circular convex portion 18 <the outer diameter D2 of the photosensitive drum 1 ≦ the outer diameter D3 of the pop-out preventing flange portion 50.

  Thus, by installing the protrusion preventing flange portion 50 of the protrusion having the outer diameter D3 larger than the outer diameter D1 of the circular convex portion 18 on the outer side in the axial direction of the circular convex portion 18, the circular convex portion 18 The toner powder does not jump out from the outer end, and the collection becomes easy.

  As shown in FIG. 13, the drum-side blade member 10 is inside the pop-out prevention flange portions 50 on both sides and has a dimensional relationship that does not contact the pop-out prevention flange portions 50.

(Tenth embodiment)
FIG. 14 is a schematic front view of a photosensitive drum unit for explaining a tenth embodiment of the present invention.
In the case of the present embodiment, two types of grooves are continuously formed on the outer peripheral surface 31 of the circular convex portion 18. That is, the spiral groove 51 is formed about 1 to 2 rounds from the inner side (photosensitive drum 1) in the axial direction to the outer side of the circular convex portion 18, and the circular convex portion is continuous with the outer end portion of the spiral groove 51. The 18 annular grooves 52 on the outer side in the axial direction are formed once.

  The toner powder scraped by the drum-side blade member 10 falls on the outer peripheral surfaces 31 of the circular protrusions 18 on both sides, and the rotation of the circular protrusions 18 and the action of the cleaning brush 12 for the circular protrusions cause the toner powder in the spiral groove 51. And move outward in the axial direction of the circular protrusion 18. The toner powder is gradually scraped to the annular groove 52 side and scraped off by the cleaning brush 12. As a result, the cleaning brush 12 is efficiently scraped, and the toner powder can be collected together.

  Since the toner powder is finally scraped together in the annular groove 52, the groove width or (and) the groove depth of the annular groove 52 is made wider than the groove width or (and) the groove depth of the spiral groove 51. Or (and) deeper.

  Similar to the embodiment shown in FIG. 10, the bottoms of the spiral groove 51 and the annular groove 52 are substantially U-shaped in cross section, and the edge of the groove opening is inclined or rounded chamfer 48. ing.

1: Photosensitive drum,
7: Development roller,
10: Blade member for drum,
11: Drum cleaning brush,
12: Cleaning brush for circular convex part,
13: Blade member for gap ensuring roller,
14: Cleaning brush for gap security roller,
15: flange body,
28: Gap guarantee roller,
30: Gap guarantee roller pressing position,
31: outer peripheral surface,
32: Stepped part,
32a: foreign matter escape recess,
33: Foreign matter,
34: coating,
37: Outer layer molding part,
39: Cover member for circular convex part,
45: Double-sided adhesive tape for circular convex part,
46: Double-sided adhesive tape for gap security roller,
47: annular groove,
48: Chamfering,
49a, 49b: spiral groove,
50: pop-out prevention flange,
51: Spiral groove,
52: annular groove,
Pg: development gap,
D1: the outer diameter of the circular convex part,
D2: outer diameter of the photosensitive drum,
D3: outer diameter of the pop-out prevention flange,
W1: width of the blade member,
W2: The width of the photosensitive drum.

JP 2007-71925 A JP 05-119602 A Japanese Patent No. 3064576 JP 2000-010316 A

Claims (19)

A cylindrical photosensitive drum;
A drum blade member in contact with the photosensitive surface of the photosensitive drum;
A flange body provided at each end opening of the photosensitive drum and having a circular convex portion protruding outward in the axial direction of the photosensitive drum;
A developing roller arranged in parallel with the photosensitive drum;
Gap ensuring rollers provided at both axially outer ends of the developing roller,
In the development gap holding mechanism in which the outer peripheral surface of the gap ensuring roller is in contact with the outer peripheral surface of the circular convex portion,
The outer diameter D1 of the circular convex portion is smaller than the outer diameter D2 of the photosensitive drum,
A developing gap holding mechanism comprising a cleaning member in contact with the outer peripheral surface of the circular convex portion. In the development gap holding mechanism according to claim 1,
A step portion provided over the entire circumference of the photosensitive drum and the circular convex portion between the photosensitive surface of the photosensitive drum and the outer peripheral surface of the circular convex portion is an outer side in the axial direction of the photosensitive surface of the photosensitive drum. A developing gap holding mechanism characterized by being adjacent to an end portion. In the development gap holding mechanism according to claim 1,
The longitudinal width L1 of the drum blade member is longer than the lateral width L2 of the photosensitive drum in the axial direction (L1> L2), and both ends of the drum blade member are in the axial direction of the photosensitive drum. A developing gap holding mechanism that protrudes outward in the axial direction from the end. In the development gap holding mechanism according to claim 1,
A developing gap holding mechanism comprising a gap ensuring roller blade member and a gap ensuring roller cleaning brush which are in contact with an outer peripheral surface of the gap ensuring roller. In the development gap holding mechanism according to claim 1,
A developing gap holding mechanism characterized in that a fluorine resin film is formed at least on the outer peripheral surface of the circular convex portion or the gap ensuring roller. In the development gap holding mechanism according to claim 1,
A developing gap holding mechanism, wherein at least an outer peripheral portion of the circular convex portion or the gap ensuring roller is constituted by an outer layer molding portion of a fluororesin. In the development gap holding mechanism according to claim 1,
The circular convex portion is covered with a circular convex portion cover member, and the gap ensuring roller is covered with a gap ensuring roller cover member,
The developing gap holding mechanism, wherein an opening is formed in the vicinity of a contact portion between the circular convex portion and the gap ensuring roller of the circular convex portion covering member and the gap ensuring roller cover member. The development gap holding mechanism according to claim 7,
The drum blade member and the drum cleaning brush are housed in the circular convex cover member,
A developing gap holding mechanism, wherein a gap ensuring roller blade member and a gap ensuring roller cleaning brush which are in sliding contact with an outer peripheral surface of the gap ensuring roller are housed in the gap ensuring roller cover member. The development gap holding mechanism according to claim 4 or 8,
The drum blade member and the drum cleaning brush are provided below the photosensitive drum in the direction of gravity;
The developing gap holding mechanism, wherein the gap ensuring roller blade member and the gap ensuring roller cleaning brush are provided below the gap ensuring roller in the direction of gravity. The development gap holding mechanism according to claim 9,
A developing gap holding mechanism, characterized in that a double-sided tape for fixing foreign matter with adhesive force is provided at least below the photosensitive drum or the gap ensuring roller in the direction of gravity. The development gap holding mechanism according to claim 9,
The drum cleaning brush is installed upstream of the drum blade member in the rotational direction of the photosensitive drum;
The developing gap holding mechanism, wherein the gap ensuring roller cleaning brush is disposed upstream of the gap ensuring roller blade member in the rotation direction of the gap ensuring roller. The development gap holding mechanism according to claim 1 or 4,
A groove is provided along the circumferential direction at least on the outer circumferential surface of the circular convex portion or the outer circumferential surface of the gap ensuring roller, and the bottom of the groove has a substantially U-shaped cross section,
A developing gap holding mechanism, wherein the opening edge of the groove is chamfered. In the development gap holding mechanism according to claim 4,
A developing gap holding mechanism, wherein spiral grooves having different lead angles are formed on the outer peripheral surfaces of the circular convex portion and the gap ensuring roller. The development gap holding mechanism according to claim 13,
The bottom of the spiral groove has a substantially U-shaped cross section,
A developing gap holding mechanism, wherein the opening edge of the spiral groove is chamfered. In the development gap holding mechanism according to claim 1,
A flange portion having an outer diameter D3 larger in diameter than an outer diameter D1 of the circular convex portion is provided concentrically with the circular convex portion on the axially outer side of the circular convex portion of the flange body. Development gap retention mechanism. The development gap holding mechanism according to claim 15,
The developing gap holding mechanism, wherein an outer diameter D1 of the circular convex portion, an outer diameter D2 of the photosensitive drum, and an outer diameter D3 of the pop-out preventing flange portion are in a relationship of D1 <D2 ≦ D3. In the development gap holding mechanism according to claim 1,
A spiral groove is formed on the outer peripheral surface of the circular convex portion from the photosensitive drum side of the circular convex portion toward the outer side in the axial direction, and the outer side in the axial direction of the circular convex portion is continuous with the outer end portion of the spiral groove. A developing gap holding mechanism, wherein an annular groove is formed in the portion. In a developing device having a developing gap holding mechanism,
18. A developing device, wherein the developing gap holding mechanism is the developing gap holding mechanism according to claim 1. In an image forming apparatus provided with a developing device,
An image forming apparatus, wherein the developing device is the developing device according to claim 18.

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