JP2006201231A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformly hold a developing gap formed by a tape type spacer over the entire peripheral surface of a developing roller and to make the spacer hard-to-peel. <P>SOLUTION: The tape type spacer 11 is spirally wound in two rounds and fixed on a toner non-conveying surface 5b. In such a case, the spirally wound direction of the spacer 11 is set to a direction where the spacer 11 advances toward the center in the shaft direction of the developing roller 5 with respect to the rotation in the set rotating direction α of the developing roller 5. The outer and inner side ends 11a and 11b of the spacer 11 are made uniform in the shaft direction of the developing roller 5 and the contact area of the photoreceptor 2 with the spacer 11 is always made fixed over the entire periphery of the spacer 11. A peripheral surface seal 13 covers over the outer peripheral surface of the toner non-conveying surface 5b inside the spacer 11 and a part of the outer peripheral surface of the spacer 11 and abuts on them. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to the technical field of image forming apparatuses such as electrophotography, electrostatic copying machines, printers, facsimiles and the like, and in particular, non-contact jumping development type images having a predetermined development gap between an image carrier and a developing roller. The present invention relates to the technical field of forming apparatuses.

  Conventionally, many image forming apparatuses using a non-contact jumping development method are known as image forming apparatuses. In this non-contact jumping development method, a predetermined development gap is provided between a photosensitive member as an image carrier and a developing roller, and toner on the developing roller is jumped to the photosensitive member to electrostatic latent image on the photosensitive member. This is a method of developing. In this non-contact jumping development method, it is required to maintain a development gap between the photosensitive member and the development roller with high accuracy in order to perform good development.

  Therefore, conventionally, a sheet-like member has been used as the developing gap adjusting member, and this sheet-like member is interposed between the outer peripheral surfaces of both ends of the developing roller and the outer peripheral surfaces of both ends of the photosensitive member, thereby developing the developing roller and the photosensitive member. It has been proposed that an appropriate development gap can be easily secured during the period (see, for example, Patent Document 1). According to the developing gap adjusting member disclosed in Patent Document 1, the developing gap between the photoconductor and the developing roller can be maintained with high accuracy.

  However, in the development gap adjusting member disclosed in Patent Document 1, since the development gap adjusting member is provided at a location different from the photosensitive member and the developing roller, the assembly of the photosensitive member, the developing roller, and the developing gap adjusting member is troublesome. In addition, depending on the assembled state, it is difficult to set the development gap with high accuracy. In addition, since the developing gap adjusting member is fixed while the photosensitive member and the developing roller rotate, the developing gap adjusting member and the photosensitive member and the developing gap adjusting member and the developing roller are rubbed. In addition, the photoconductor and the developing roller are worn, and it is difficult to maintain an accurate developing gap.

  On the other hand, a film member (corresponding to the tape-like spacer of the present invention) is wound and fixed on the outer peripheral surface of both ends of the charging roller, and the image carrier is brought into contact with these film members, so that the charging roller and the image carrier It has been proposed to perform proximity charging by providing a predetermined charging gap between them (for example, see Patent Document 2).

In the charging gap adjustment disclosed in Patent Document 2, both end portions of the film member in the circumferential direction are cut obliquely, and both end edges cut obliquely are opposed to each other so as to form a gap between them, A film member is present in the axial direction of the charging roller at all positions around the charging roller to ensure a constant charging gap.
Therefore, according to the charging gap adjustment disclosed in Patent Document 2, since the film member is fixed to the charging roller, it is easy to assemble the photoconductor, the charging roller and the film member, and the charging gap can be easily increased. The accuracy can be set.
Japanese Patent Laid-Open No. 5-27571. JP 2001-296723 A.

By the way, it is conceivable that the charging gap adjustment disclosed in Patent Document 2 is applied to the developing gap adjustment, and this developing gap adjustment is performed easily and with high accuracy. However, in the case of developing gap adjustment, the contact pressure at which the film member fixed to the developing roller contacts the photosensitive member as the image bearing member is set higher than the contact pressure of the film member fixed to the charging roller to the photosensitive member. Has been. Therefore, if there is a gap S between the opposite ends b _1, b ₂ of the developing roller a end-wound film member b of, as shown in FIG. 5, both end edges b ₁ of the film member b, b ₂ The film member b is exposed to the photosensitive member at the position A where there is no gap S other than the case B and the photosensitive member is contacted at the position B where the gap S between the both ends b ₁ and b ₂ of the film member b is contacted. Due to the contact pressure on the body, the linear pressure applied to the film member b is greater at the position B than at the position A (linear pressure at the position A <linear pressure at the position B). ). Therefore, the development gap at position A is larger than the development gap at position B (development gap at position A> development gap at position B). For this reason, the part of the position B, that is, the joint part of the film member b appears as horizontal stripes in the image.

Further, when both end edges b ₁ , b ₂ of the film member b are cut obliquely and a gap S is formed between them, the film member b has both end edges b ₁ , b ₂ , particularly both end edges b ₁ , b ₂ . There is also a problem of peeling off from the tip and turning up. In that case, in order to prevent the toner from leaking from the end of the developing roller a in the developing roller a, the peripheral surface seal c is disposed so as to contact the outer peripheral surface of the end of the developing roller a. As compared with a charging roller that does not require a peripheral surface seal, the film member b is peeled off from both end edges b ₁ and b ₂ and is easily turned up.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a developing roller with a developing gap that can be easily and accurately adjusted with a tape-like spacer. It is an object of the present invention to provide an image forming apparatus for non-contact development that can be held uniformly over the entire circumference of the sheet and that makes it difficult to remove the spacer.

  In order to solve the above-mentioned problems, an image forming apparatus according to a first aspect of the present invention is provided with an image carrier and a toner conveying surface provided so as to face each other with a predetermined development gap therebetween. At least a developing roller that conveys toner to the carrier and a gap adjusting member that is provided at both ends of the developing roller and sets the development gap by contacting the image carrier, and performs non-contact jumping development In the image forming apparatus, the gap adjusting member is constituted by a tape-like spacer, and the spacer is spirally wound around the outer peripheral surfaces of both end portions of the developing roller and fixed to the image carrier. The contact area is made constant, and further, the spiral winding direction of the spacer is set so that the spacer rotates with respect to the rotation of the developing roller in the set rotation direction. It is characterized in that it is set to a direction of advancing toward the axial center of the over la.

  The invention according to claim 2 further includes a seal member disposed at both ends of the developing roller, wherein the seal member is an outer peripheral surface axially central from the spacer of the developing roller and a shaft of the developing roller. It is characterized by being disposed across the outer peripheral surface of a part of the spacer adjacent to the outer peripheral surface on the center side in the direction.

According to the image forming apparatus of the present invention configured as described above, since the development gap is set by the tape-like spacers fixed to both ends of the development roller, the development gap is easily adjusted with high accuracy. Will be able to.
In addition, a tape-like spacer is spirally wound around both ends of the developing roller to eliminate the gap at the joint of the spacer, and the contact area between the image carrier and the spacer is set constant, so that the entire circumferential surface of the spacer Thus, the contact pressure of the spacer to the image carrier can be kept equal. Therefore, the predetermined development gap g can always be kept uniform, and horizontal stripes due to the joint portion of the spacer can be prevented in the obtained image. Thereby, a high quality image can be obtained.

  Further, since the spiral winding direction of the spacer is set to a direction in which the spacer advances toward the center in the axial direction of the developing roller with respect to the rotation of the developing roller set, the toner is spirally wound by the spacer. It can be made to discharge to the axial center side of the developing roller. Thereby, the sealing performance of the toner at both ends of the developing roller can be improved.

  In particular, according to the second aspect of the present invention, since the force by the seal member is not applied to each inner end of the spacer so that the inner end is peeled off from the developing roller, the seal member is applied to a part of the outer peripheral surface of the spacer. Even if it is put in contact, it can be prevented that each inner end of the spacer is peeled off from the developing roller by the sealing member. Further, since the seal member is not brought into contact with each outer end of the spacer, each outer end of the spacer can be prevented from being peeled off from the developing roller by the seal member. Thereby, the durability of the spacer can be improved, and a predetermined development gap can be uniformly maintained over a long period of time. In particular, in combination with a spirally wound spacer, the toner sealing performance at both ends of the developing roller can be further improved.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 schematically shows a developing cartridge in which a developing device and a photosensitive member are integrally formed, which is used in an example of an embodiment of an image forming apparatus according to the present invention. b) is a partial view of the developing cartridge of this example.

  As shown in FIGS. 1A and 1B, the developing cartridge 1 of the image forming apparatus of this example includes an image carrier (in this example, a drum-shaped photosensitive member 2; ) And the developing device 3 are integrated as an image carrier-developing device integrated cartridge (in this example, a photosensitive member-developing device integrated cartridge).

  The developing device 3 includes a developing roller 5 that conveys the toner T to the photosensitive member 2, a supply roller 6 that is pressed against the developing roller 5 to supply the toner T, and a toner T that is pressed against the developing roller 5 and conveyed to the photosensitive member 2. A regulating blade 7 for regulating, a toner agitating and conveying member 8 for agitating and conveying the toner T, a toner receiving member 9 for receiving the toner T conveyed by the toner agitating and conveying member 8 and guiding it toward the supply roller 6, and a developing roller 5 is provided with an upper seal 10 for preventing toner leakage while abutting in the direction of collecting the toner T remaining after development. The photosensitive member 2, the developing roller 5, the supply roller 6, the regulating blade 7, the toner stirring and conveying member 8, and the toner receiving member 9 are all disposed in the photosensitive member-developing device integrated case 4.

  As shown in FIG. 2, the photoreceptor 2 has an image carrying surface 2a formed at the center thereof and image non-carrying surfaces 2b and 2c formed at both ends thereof. Further, the developing roller 5 has a toner non-conveying surface 5a formed at the center thereof, and toner non-conveying surfaces 5b and 5c formed at both ends thereof. For the developing roller 5, a metal roller such as iron or a resin such as urethane that has extremely small stress shrinkage and thermal shrinkage is used.

  Tape-like spacers 11 and 12 are fixed to the toner non-conveying surfaces 5b and 5c, respectively, on the toner non-conveying surfaces 5b and 5c of the developing roller 5. The spacers 11 and 12 are pressed against the image non-carrying surfaces 2b and 2c of the photosensitive member 2, whereby the toner conveying surface 5a of the developing roller 5 and the image carrying surface 2a of the photosensitive member 2 facing the toner conveying surface 5a. A development gap g is formed between the two.

  The developing gap g is accurately set to a desired size by appropriately selecting the thicknesses of the spacers 11 and 12. As a result, the developing device 3 performs non-magnetic one-component developer non-contact jumping development using the toner T which is a non-magnetic one-component developer. In that case, in the image carrier-developer-integrated cartridge 1 of this example, the photosensitive member 2 rotates clockwise as shown in FIG. 1B, and the developing roller 5 and the supply roller 6 both counterclockwise. It is set to rotate. The peripheral speed of the photosensitive member 2 and the peripheral speed of the spacers 11 and 12 on the developing roller 5 are set to be the same or substantially the same.

  As shown in FIG. 3, specifically, the spacer 11 is fixed by being spirally wound around the toner non-transport surface 5b over two rounds. In that case, the spiral winding direction of the spacer 11 is set to a direction in which the spacer 11 advances toward the center in the axial direction of the developing roller 5 with respect to the rotation of the developing roller 5 in the rotation direction α. Further, the side edge on the developing roller end side of the second-round spacer 11 is in close contact with the side edge on the developing roller center side of the first-round spacer 11. Further, an end 11a of the spacer 11 on the developing roller end side (hereinafter referred to as an outer end) and an end 11b of the spacer 11 on the center side of the developing roller (hereinafter referred to as an inner end) are aligned in the axial direction of the developing roller 5. (That is, both ends 11a and 11b are located on one straight line in the axial direction of the developing roller 5). As a result, the contact area between the photoconductor 2 and the spacer 11 is always constant, and the development gap g is secured constant over the entire circumference of the development roller 5.

  In the illustrated example, the tape-like spacer 11 is spirally wound twice. However, the spiral winding is not limited to this, and may be spirally wound once or three or more times. In the case of spiral winding of three or more rounds, the side edge on the developing roller end side of the spacer 11 in the second and subsequent rounds is brought into close contact with the side edge on the developing roller central side of the spacer 11 one round before.

  Although not shown, the tape-like spacer 12 is also spirally wound and fixed to the toner non-transport surface 5c in exactly the same manner as the spacer 11 (note that the spiral winding direction of the spacer 12 is apparently the center of the developing roller 5 in the axial direction) Is symmetrical with the spiral winding direction of the spacer 11).

  Further, the spacers 11 and 12 fixed by being wound spirally on the developing roller 5 are made of an elastic body, and as the elastic body, preferably, polyamide, polyamideimide, fluororesin, polyester, polyolefin, Plastics and rubbers such as polyimide, epoxy, acetate, silicone, acrylic and rubber are used. In that case, it is preferable that the elastic body used for the spacers 11 and 12 is an insulator, and it is preferable to use an adhesive tape as the spacers 11 and 12 in terms of ease of attachment and tolerance.

  Further, circumferential seals (corresponding to a seal member of the present invention) 13 and 14 are disposed on both ends of the developing roller 5 so as to straddle the outer circumferential surface of the developing roller 5 and the outer circumferential surfaces of the spacers 11 and 12. Yes. Specifically, most of these peripheral surface seals 13 and 14 are inside the spacers 11 and 12 (on the center side in the axial direction of the developing roller 5) of the toner non-conveying surfaces 5b and 5c of the developing roller 5, respectively. It is disposed so as to face almost the entire surface of the substantially half circumference, and the remaining portion is arranged to face a part of the substantially half circumference of the spacers 11 and 12. Therefore, the peripheral surface seals 13 and 14 are configured not to contact the outer ends 11a and 12a of the spacers 11 and 12, respectively. These peripheral surface seals 13 and 14 can be brought into contact with almost the entire surface of the toner non-conveying surfaces 5b and 5c and part of the outer peripheral surfaces of the spacers 11 and 12, respectively, and the toner on the developing roller 5 is developed. Leakage from both ends of the roller 5 is prevented.

  In the image forming apparatus 1 configured as described above, the tape-like spacers 11 and 12 are fixed by being spirally wound around the toner non-conveying surfaces 5 b and 5 c at both ends of the developing roller 5. Since there is no gap between both end edges, that is, at the joints of the spacers 11 and 12, and the contact area between the photosensitive member 2 and the spacers 11 and 12 is set to be constant, The contact pressure of the spacers 11 and 12 to the photosensitive member 2 is kept equal. Therefore, when the developing roller 5 is rotated in the rotation direction α set at the time of image formation or the like, the predetermined developing gap g is always kept uniform, and horizontal stripes due to the joint portions of the spacers 11 and 12 do not appear in the obtained image.

  Further, when the developing roller 5 rotates in the set rotation direction α, the peripheral surface seals 13 and 14 in contact with the spacers 11 and 12 move so as to escape from the inner ends 11b and 12b of the spacers 11 and 12, respectively. To do. Therefore, the inner ends 11b and 12b of the spacers 11 and 12 act so that the force by the peripheral seals 13 and 14 presses the inner ends 11b and 12b against the developing roller 5, but the inner ends 11b and 12b It does not act to peel 12b from the developing roller 5. As a result, even if the peripheral surface seals 13 and 14 are put on and contacted with a part of the outer peripheral surfaces of the spacers 11 and 12, when the developing roller 5 rotates in the rotation direction α, each inner end of the spacers 11 and 12 11b and 12b are not peeled off from the developing roller 5 by the peripheral seals 13 and 14. Further, since the circumferential seals 13 and 14 do not contact the outer ends 11a and 12a of the spacers 11 and 12, when the developing roller 5 rotates in the rotation direction α, the outer ends 11b and 12b of the spacers 11 and 12 also The peripheral seals 13 and 14 are not peeled off from the developing roller 5 and turned up.

  Further, the spiral winding direction of the spacers 11 and 12 is set in a direction in which the spacers 11 and 12 advance toward the center in the axial direction of the developing roller 5 with respect to the rotation of the developing roller 5 in the set rotation direction α. Thus, when the developing roller 5 rotates in the rotation direction α, the toner moving toward both ends of the developing roller 5 is discharged to the axially central side of the developing roller 5 by the spirally wound spacers 11 and 12 (returned back). Be) As a result, in combination with the peripheral surface seals 13 and 14, the toner that leaks from both ends of the developing roller 5 is more effectively sealed.

According to the image forming apparatus 1 of this example, since the developing gap g is set by the tape-like spacers 11 and 12 fixed to both ends of the developing roller 5, the developing gap is easily adjusted with high accuracy. Will be able to.
Further, the tape-like spacers 11 and 12 are spirally wound around both ends of the developing roller 5 to eliminate a gap at the joint between the spacers 11 and 12, and the contact area between the photosensitive member 2 and the spacers 11 and 12 is set constant. Therefore, the contact pressures of the spacers 11 and 12 to the photosensitive member 2 can be equally maintained on the entire peripheral surfaces of the spacers 11 and 12. Therefore, the predetermined development gap g can be always maintained uniformly, and the occurrence of horizontal stripes due to the joint portions of the spacers 11 and 12 can be prevented in the obtained image. Thereby, a high quality image can be obtained.

  Further, since the force by the circumferential seals 13 and 14 does not act on the inner ends 11b and 12b of the spacers 11 and 12 so that the inner ends 11b and 12b are peeled off from the developing roller 5, the circumferential seals 13 and 14 Even when the spacers 11 and 12 are in contact with a part of the outer peripheral surface of the spacers 11 and 12, the inner ends 11b and 12b of the spacers 11 and 12 are prevented from being peeled off from the developing roller 5 by the peripheral seals 13 and 14. it can. Further, since the circumferential seals 13 and 14 are not brought into contact with the outer ends 11 a and 12 a of the spacers 11 and 12, the outer ends 11 b and 12 b of the spacers 11 and 12 are also peeled off from the developing roller 5 by the circumferential seals 13 and 14. Can be prevented from turning up. Thereby, the durability of the spacers 11 and 12 can be improved, and the predetermined development gap g can be uniformly maintained over a long period of time.

  Further, the spiral winding direction of the spacers 11 and 12 is set to a direction in which the spacers 11 and 12 advance toward the center in the axial direction of the developing roller 5 with respect to the rotation of the developing roller 5 in the rotational direction α. The toner can be discharged to the center in the axial direction of the developing roller 5 by the spirally wound spacers 11 and 12. Thereby, the sealability of the toner at both ends of the developing roller 5 can be improved in combination with the peripheral surface seals 13 and 14.

  On the other hand, as shown in FIG. 4, the spacers 11, 12 advance toward both ends of the developing roller 5 in the spiral winding direction of the spacers 11, 12 with respect to the rotation of the developing roller 5 in the set rotation direction α. When the direction is set, the inner ends 11b and 12b of the spacers 11 and 12 move so as to enter the circumferential seals 13 and 14 when the developing roller 5 rotates in the rotation direction α. For this reason, the inner end 11b, 12b of the spacer 11, 12 acts so that the inner end 11b, 12b is peeled off from the developing roller 5 by the force of the peripheral seal 13, 14, so that the peripheral seal 13, The inner ends 11b and 12b of the 14 are peeled off from the developing roller 5 and are easily turned up. Therefore, the durability of the spacers 11 and 12 is lowered, and the predetermined development gap g cannot be kept uniformly over a long period of time.

  The developing device according to the present invention is an image forming apparatus that forms an electrostatic latent image on an image carrier such as an electrophotographic, electrostatic copying machine, printer, or facsimile, and has a predetermined development gap between the image carrier and the developing roller. It can be suitably used for a non-contact jumping development type development apparatus having

1 schematically shows a developing cartridge in which a developing device and a photosensitive member are integrally formed, which is used in an example of an embodiment of an image forming apparatus according to the present invention. FIG. FIG. 3 is a partial view of an example developing cartridge. FIG. 2 is a diagram schematically showing a developing gap by a spacer in the developing device of the example shown in FIG. 1. FIG. 3 is a partial view schematically and partially showing the spacer of the present invention shown in FIG. 2. FIG. 4 is a partial view schematically and partially showing a spacer for comparison with the spacer of the present invention shown in FIG. 3. It is a figure explaining the problem at the time of using the charging gap adjustment by the conventional film member for development gap adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Developing cartridge, 2 ... Photoconductor (image carrier), 3 ... Developing device, 6 ... Supply roller, 11, 12 ... Spacer, 11a, 12a ... Outer end of spacer 11, 12, 11b, 12b ... Spacer 11, 12 inner end, 13, 14 ... peripheral seal, g ... development gap

Claims (2)

An image carrier, a developing roller provided with a toner conveyance surface facing the image carrier with a predetermined development gap therebetween, and a toner roller for conveying toner to the image carrier; and provided at both ends of the developing roller. An image forming apparatus for performing non-contact jumping development, comprising at least a gap adjusting member that sets the development gap by contacting the image carrier.
The gap adjusting member is composed of a tape-shaped spacer,
The spacer is fixed by being spirally wound around the outer peripheral surface of both end portions of the developing roller, and the contact area with the image carrier is constant, and the spiral winding direction of the spacer is The image forming apparatus according to claim 1, wherein the spacer is set in a direction that advances toward an axial center of the developing roller with respect to rotation of the developing roller in a set rotating direction. A seal member disposed at both ends of the developing roller, the seal member being adjacent to an outer peripheral surface on an axially central side of the spacer of the developing roller and an outer peripheral surface on an axially central side of the developing roller; The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed across a part of the outer peripheral surface of the spacer.

Images