JP2007033620A - Gap holding member and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gap holding member capable of removing toner stuck to the surface of an image carrier such as a photoreceptor while suppressing its cost from rising, and an image forming apparatus having the gap holding member. <P>SOLUTION: A developing roll 42 is arranged to be opposed to the image carrier 26. The gap holding members 66 and 66 are provided coaxially to the rotary shaft of the developing roll, and rotated in contact with the image carrier 26, whereby an axle-to-axle distance between the image carrier and the developing roll is kept constant. Many grooves 70 inclined obliquely are formed on the surfaces of the gap holding members 66 and 66, and the toner adhering to the gap holding part is scraped by the groove 70. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spacing member and an image forming apparatus having the same.

As an image forming apparatus such as a copying machine, a printer, a facsimile, or the like, there is a xerographic system. As an example of the xerographic system, the surface of the photoconductor is uniformly charged by a charging device, and the photoconductor is subjected to, for example, a laser exposure device. A latent image is formed, the latent image formed on the photosensitive member is visualized as a toner image by a developing device, the visualized toner image is transferred to a sheet by a transfer device, and the transferred toner An image fixing apparatus is known that fixes an image onto a sheet. For example, a rotating photosensitive drum is used as the photoreceptor, and a developing roll provided so as to face the photoreceptor is used as the developing device. In such an image forming apparatus, in order to obtain a stable quality image, it is necessary to maintain a constant axial distance between the photosensitive drum and the developing roll. For this reason, an interval holding member is provided coaxially with the central axis of the developing roll, and the interval holding member is pressed against the photosensitive drum and rotated (for example, Patent Document 1).
When a transfer roll is used as the transfer device, a spacing member may be provided coaxially with the transfer roll (for example, Patent Document 2).

JP 2000-098856 A JP 09-218549 A

However, for example, toner and carrier from the developing roll, etc., enter the interval holding portion, and are fixed as time passes, causing vibration and rotational fluctuation, which is a cause of image quality deterioration.
As a countermeasure against this, a method is known in which a cleaning member is pressed against a spacing member and toner adhering to the spacing member is wiped off by the cleaning member (for example, Patent Documents 1 and 2).
However, in addition to the cost increase due to the provision of the cleaning member, the load for rotating the developing roll is increased, which leads to an increase in cost on the driving side of the developing roll.

  An object of the present invention is to provide an interval holding member that can remove toner adhering to the surface of an image carrier such as a photoconductor and an image forming apparatus having the same while suppressing an increase in cost.

The first feature of the present invention is that it is provided on the same axis as the central axis of the opposing roll facing the image carrier, contacts the image carrier, and maintains a constant distance between the opposing roll axes. In the holding member, the gap holding member has a groove formed obliquely with respect to the central axis of the opposed roll. Therefore, since the slant groove is formed on the surface of the spacing member, if there is a difference in peripheral speed between the image carrier and the opposing roll, slip occurs between the two, and this slip causes the slant groove to pass through the slant groove. It is possible to scrape off the toner that is about to adhere to the interval holding portion.
The image carrier includes a photoreceptor and an intermediate transfer member. Further, the facing roll includes a developing roll and a transfer roll.

  Preferably, the groove rotates with the rotation of the image carrier, and the groove is inclined so that the inner end is on the upstream side in the rotation direction and the outer end is on the downstream side in the rotation direction. Accordingly, since the spacing member rotates in accordance with the rotation of the image carrier, the circumferential speed of the spacing member is slower than the circumferential speed of the image carrier, the groove has the inner end on the upstream side in the rotation direction, and the outer end rotates. If it is formed so as to be on the downstream side in the direction, a component force directed to the outside acts on the toner scraped off by the groove, and the toner can be discharged to the outside of the interval holding portion.

  More preferably, when the plurality of grooves are formed and cut along a plane passing through the central axis of the opposed roll, the plurality of grooves cross the side where the cut surface and the surface of the spacing member intersect. To do. As a result, the spacing member contacts the image carrier at a plane portion excluding the grooves in the axial direction, so that the spacing member can always be brought into contact with the image carrier at a target outer diameter during rotation, and the spacing member is originally intended. The toner can be scraped off without impairing the securing of the inter-axis distance.

  The second feature of the present invention is that an image carrier, an opposing roll facing the image carrier, and a distance maintaining coaxially with the central axis of the opposing roll and contacting the image carrier. And the spacing member is in an image forming apparatus in which a groove that is inclined with respect to the central axis of the opposing roll is formed on the surface.

  The image carrier is a photoreceptor or an intermediate transfer member, and the opposing roll is a developing roll or a transfer roll when the image carrier is a photoreceptor, and a transfer roll when the image carrier is an intermediate transfer member.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 is provided on the upper portion of the image forming apparatus main body 12. A sheet feeding device 18 to be described later is provided below the image forming apparatus main body 12.

  The discharge unit 16 includes an inclined portion 22 that is rotatable with respect to the image forming apparatus main body 12. The inclined portion 22 has a low discharge port portion, and is inclined so as to gradually increase toward the front surface direction (the right direction in FIG. 1), with the discharge port portion as a lower end and a higher tip as an upper end. The inclined portion 22 is supported by the image forming apparatus main body 12 so as to be rotatable about the lower end. As shown by a two-dot chain line in FIG. 1, when the inclined portion 22 is rotated upward and opened, an open portion 24 is formed, and a process cartridge 40 described later can be attached and detached through the open portion 24. .

  The image forming means 14 is of, for example, an electrophotographic system, and includes an image carrier 26 made of a photosensitive member, a charging device 28 made of, for example, a charging roll that uniformly charges the image carrier 26, and charged by the charging device 28. An optical writing device 30 that writes a latent image on the image carrier 26 by light, a developing device 32 that visualizes the latent image of the image carrier 26 formed by the optical writing device 30 with toner, and the developing device 32 A transfer device 34 composed of, for example, a transfer roll for transferring the toner image on the sheet, a cleaning device 36 composed of, for example, a blade for cleaning the toner remaining on the image carrier 26, and a toner image on the sheet transferred by the transfer device 34. For example, a fixing device 38 composed of a pressure roll and a heating roll. The optical writing device 30 is composed of, for example, a scanning type laser exposure device, and is arranged in the vicinity of the front surface (right side surface in FIG. 1) of the image forming apparatus main body 12 in parallel with the paper feeding cassette 20 of the paper feeding device 18. The image carrier 26 is exposed across the. Further, the developing device 32 has a developing roll 42 that faces the image carrier 26.

  The process cartridge 40 is obtained by integrating the image carrier 26, the charging device 28, the developing device 32, and the cleaning device 36. The process cartridge 40 is disposed immediately below the inclined portion 22 of the discharge portion 16 and is attached / detached via the opening portion 24 formed when the inclined portion 22 is opened as described above.

  In the image forming apparatus main body 12, for example, a resist roll 44 is disposed on the upstream side (lower side in FIG. 1) of the transfer device 34. The sheet conveyed from the sheet feeding device 18 to the conveyance path 45 is temporarily stopped by the registration roll 44 and sent to the image forming unit 14 at a predetermined timing to form an image. The sheet is discharged to the discharge unit 16 by the discharge roll 46. Is done.

  However, in the case of duplex printing, it is returned to the reverse path. That is, the front side of the discharge roll 46 is divided into two forks, and a switching claw 48 is provided at the divided portion, and an inversion path 50 is formed to return from the divided portion to the registration roll 44. The reversing path 50 is provided with transport rolls 52a to 52c. In the case of double-sided printing, the switching claw 48 is switched to the side that opens the reversing path 50, and the discharge roll 46 is in front of the rear end of the sheet. Thus, the discharge roll 46 is reversed, the sheet is guided to the reverse path 50, and is discharged to the discharge unit 16 through the resist roll 44, the transfer device 34 and the image carrier 26, and the fixing device 38.

  The paper feeding device 18 includes a paper feeding cassette 20 and a paper feeding device main body 54 in which the paper feeding cassette 20 is stored. The sheet feeding apparatus main body 54 is formed integrally with the image forming apparatus main body 12 described above, and the front side of the image forming apparatus 10 is opened to receive the sheet feeding cassette 20. The feed roll 60 is supported by the sheet feeding device main body 54, and the retard roll 62 is supported by the sheet feeding cassette 20. The feed roll 60 and the retard roll 62 are in contact with each other, and the uppermost position of the sheet feeding cassette 20. The paper is picked up, and the paper is collaborated in cooperation.

  In FIG. 2, the relationship between the image carrier 26 and the developing roll 42 is shown. The developing roll 42 provided to face the image carrier 26 is fixed to rotating shafts 64 and 64 provided on both sides, and rotates around the center of the rotating shafts 64 and 64 as a central axis. Spacing members 66 and 66 are rotatably provided on the rotary shafts 64 and 64 on both sides. The spacing members 66, 66 are, for example, molded products of polyacetal resin, and are formed in a ring shape. The spacing members 66, 66 are in contact with the image carrier 26, receive the driving force of the image carrier 26, and rotate in the opposite direction to the image carrier 26 on the same axis as the central axis of the developing roll 42. . The rotating shafts 64 and 64 are urged toward the image carrier by elastic bodies 68 and 68 made of springs, for example. The image carrier 26 is rotated in one direction by a driving force from a drive source (not shown), and the rotation of the image carrier 26 rotates the developing roll 42 in the opposite direction to the image carrier 26 via a gear train (not shown), for example. It is configured to let you. Accordingly, since the developing roll 42 rotates in a state where the spacing members 66 and 66 are pressed against the image carrier 26 via the rotation shafts 64 and 64, the gap between the image carrier 26 and the developing roll 42 is kept constant. Can be kept in.

  As shown in FIGS. 3 and 4, the spacing member 66 has a number of grooves 70 formed on the surface of the spacing member 66. As indicated by the arrows in FIG. 3, the groove 70 is located on the upstream side in the rotation direction of the spacing member 66 (opposite to the rotation direction of the image carrier 26 and coincides with the rotation direction of the developing roller 42). An end (developing roll side end) is formed, and the outer end (anti-developing roll side end) is inclined, for example, in a straight line so as to be downstream in the rotation direction.

  Further, as shown in FIG. 4, the groove 70 of the spacing member 66 has a plurality of sides where the cut surface P and the surface of the spacing member 66 intersect when cut along a plane P passing through the central axis of the developing roll 42. Two books, for example two, cross.

  In the above configuration, the image carrier 26 is uniformly charged by the charging device 28, a latent image is formed on the charged image carrier 26 by the optical writing device 30, and the latent image on the image carrier 26 is developed by a developing device. The toner image is developed by a toner image 32, transferred to a sheet by a transfer device 34, and the toner remaining on the image carrier 26 is cleaned by a cleaning device 36.

  During the developing operation, the image carrier 26 and the developing roll 42 rotate in the opposite directions, and the toner on the developing roll 42 (via a carrier in the case of a two-component system) is transferred to the image carrier 26 and is transferred to the image. A toner image is formed on the carrier 26. At this time, since the developing roll 42 rotates in a state where the spacing members 66 and 66 are pressed against the image carrier 26, the gap between the image carrier 26 and the developing roll 42 can be kept constant.

  However, a part of the toner on the image carrier 26 or the developing roll 42 goes around the interval holding portion and tries to adhere to the image carrier 26 or the interval holding members 66 and 66. However, since the spacing members 66 and 66 are driven and rotated by the rotation of the image carrier 26, the peripheral speed differs, and the spacing members 66 and 66 are formed with a large number of oblique grooves 70. Alternatively, the toner that tends to adhere to the spacing members 66, 66 is scraped off by the groove 70. Moreover, the groove 70 is formed obliquely so that the inner end is on the upstream side in the rotation direction of the spacing member 66 and the outer end is on the downstream side in the rotation direction. Therefore, a component force toward the outside acts, and the toner can be discharged to the outside of the interval holding portion. In addition, since the plurality of grooves 70 always cross the image carrier 70 and the surface portions of the spacing members 66 and 66 are in contact with the image carrier 26, the spacing members 66 and 66 always have a desired outer shape during rotation. 26, the distance between the axes of the image carrier 26 and the developing roll can be secured.

  In the above embodiment, the spacing members 66, 66 are ring-shaped and are rotatably supported by the rotation shafts 64, 64 of the developing roll 42. However, the present invention is not limited to this. As an embodiment, the spacing members 66 and 66 may be formed in a cap shape and fitted and fixed to the end portion of the developing roll 42. In this case, the peripheral speed difference between the image carrier 26 and the developing roll 42 can be ensured by adjusting the driving side for driving the developing roll 42.

  As described above, the present invention can be used for an image forming apparatus that needs to remove toner adhering to the surface of an image carrier without causing an increase in cost.

1 is a side view showing an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a side view showing a relationship between an image carrier and a developing roll according to an embodiment of the present invention. FIG. 3 is an enlarged side view showing a space holding portion between an image carrier and a developing roll according to an embodiment of the present invention. It is a side view which shows the space | interval holding member which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 14 Image forming means 18 Paper feeding apparatus 26 Image carrier 28 Charging apparatus 38 Fixing apparatus 42 Developing roll 64 Rotating shaft 66 Spacing holding member 70 Groove

Claims (6)

  An interval holding member that is provided coaxially with the center axis of the opposing roll facing the image carrier and is in contact with the image carrier and maintains a constant distance between the opposing roll axes, with respect to the central axis of the opposing roll An interval holding member, wherein a groove inclined obliquely is formed on the surface.   2. The groove according to claim 1, wherein the groove rotates with the rotation of the image carrier and is inclined so that the inner end is on the upstream side in the rotation direction and the outer end is on the downstream side in the rotation direction. Spacing member.   A plurality of the grooves are formed, and the plurality of grooves cross a side intersecting with the cut surface and the surface of the spacing member when cut by a plane passing through the central axis of the facing roll. The interval holding member according to 1 or 2.   An image carrier, an opposing roll that faces the image carrier, and a spacing member that is provided coaxially with the central axis of the opposing roll and contacts the image carrier, the spacing member being An image forming apparatus, wherein a groove that is inclined with respect to a central axis of the opposing roll is formed on a surface.   The image forming apparatus according to claim 4, wherein the facing roll is a developing roll.   The image forming apparatus according to claim 4, wherein the facing roll is a transfer roll.

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