JP4457698B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copying machines and printers using an electrophotographic system (electrostatic transfer system) are widely known. In such an image forming apparatus, when the toner visible image on the photosensitive drum is transferred to the sheet side, a predetermined charge is supplied from the back side of the sheet, and the toner visible image is formed by utilizing the suction force of the charge. It is configured to transfer to paper.

  This charge is appropriately neutralized from the back side of the sheet using a neutralization unit in order to prevent a situation that hinders the smooth conveyance of the sheet, such as generation of the sheet JAM, after the toner visible image is transferred to the sheet.

  Usually, the static elimination means needs to be grounded to release electric charges. However, since the design and manufacturing process is complicated, a conductive fiber member that does not need to be grounded may be used as the static elimination means.

  Since the conductive fiber member has a so-called self-discharge effect, it can be well removed by repeating the discharge delicately from the end faces of the conductive fibers that are intertwined in a complicated manner. .

  However, when the conductive fiber member is used as the charge eliminating unit as described above, fluffing of fibers due to static electricity occurs from the surface of the conductive fiber member 100 as shown in FIG. When the surface is touched, the charge may be excessively removed. If the charge accumulated on the paper P is excessively removed, the attractive force of the toner image formed on the paper P is weakened and the image is disturbed, resulting in a problem that the image quality deteriorates.

  In addition, when the neutralization means is provided with a gap between the paper so that the fluff of the conductive fibers does not contact the paper, the charges accumulated on the paper cannot be sufficiently removed, and therefore the above-mentioned Such a paper JAM or the like causes a problem that the smooth conveyance of the paper is hindered.

  Further, when the conductive member is arranged so as to contact the paper, there is a problem that the floating toner in the apparatus adheres to the conductive member and the front end of the paper is soiled.

  For this reason, a method of further overlapping a conductive member on the conductive fiber member has also been proposed (see, for example, Patent Document 1).

However, when the transfer is repeated several times as in a color image forming apparatus, the voltage applied to the paper is also higher than that of the monochrome image forming apparatus, and a sufficient neutralizing effect cannot be obtained if the conductive fiber member is not contacted. There is.
JP 2001-278486 A (FIG. 3, pages 3-4)

  SUMMARY OF THE INVENTION In consideration of the above facts, an object of the present invention is to provide an image forming apparatus that has excellent transportability and image quality and is less likely to cause stains on the back side of a sheet.

The image forming apparatus according to claim 1, wherein at least one latent image carrier on which a toner image is formed on a surface, and a toner image formed on the surface of the latent image carrier are provided with at least one intermediate transfer member. An image forming apparatus including: a transfer unit that directly or directly transfers onto a transfer material; and a charge eliminating unit that is provided downstream of the transfer unit in the transfer material conveyance direction and removes the electric charge accumulated in the transfer material. The discharging means is disposed on the transfer fiber of the conductive fiber member, and the conductive fiber member biased in the direction facing and contacting the non-image forming surface of the transfer material on the downstream side in the transport direction. A spacer member provided on the opposite surface and in contact with the transfer material , wherein the spacer member has a serrated shape with concavities and convexities extending in a direction orthogonal to the transfer direction of the transfer material, and the convexity of the spacer member. Part is the conductive fiber part Characterized in that it extends to the tip of the downstream side of the transfer material in the.

In the invention with the above configuration, excess charge is removed from the back side of the transfer material by the charge eliminating means, and the charge eliminating means is not in direct contact with the transfer material by the spacer member. it can. In other words, the serrated convex portion extends to the tip of the conductive fiber member and prevents contact between the paper and the conductive fiber member, while the presence of the concave portion can reduce the distance between the conductive fiber member and the paper. As a result, the static elimination effect can be enhanced.

The image forming apparatus according to claim 2, wherein at least one latent image carrier on which a toner image is formed and a toner image formed on the surface of the latent image carrier are provided with at least one intermediate transfer member. An image forming apparatus including: a transfer unit that directly or directly transfers onto a transfer material; and a charge eliminating unit that is provided downstream of the transfer unit in the transfer material conveyance direction and removes the electric charge accumulated in the transfer material. The neutralizing means is provided on the downstream side in the transport direction so as to contact a non-toner image transfer surface of the transfer material, and a spacer member that contacts the non-toner image transfer surface of the transfer material via the spacer member. The spacer member has a sawtooth shape with concavities and convexities extending in a direction orthogonal to the transfer direction of the transfer material, and the convex portion of the spacer member is in the conductive fiber member. The transfer material Characterized in that it extends to the tip of the downstream side in the conveying direction.

In the invention with the above configuration, excess charge is removed from the back side of the transfer material by the charge eliminating means, and the charge eliminating means is not in direct contact with the transfer material by the spacer member. it can. In other words, the serrated convex portion extends to the tip of the conductive fiber member and prevents contact between the paper and the conductive fiber member, while the presence of the concave portion can reduce the distance between the conductive fiber member and the paper. As a result, the static elimination effect can be enhanced.

The image forming apparatus according to claim 3, wherein a plurality of latent image carriers that respectively form toner images of different colors are formed on the surface, an endless belt-shaped conveyance member that conveys a transfer material, and the plurality of latent images. A plurality of transfer means for transferring the toner image formed on the surface of the carrier onto the transfer material in a multiplex manner, and provided on the downstream side of the transfer means in the transfer material transport direction, the charge accumulated on the transfer material is An image forming apparatus provided with a static eliminating unit for removing the conductive fiber, wherein the static eliminating unit is urged in a direction facing and in contact with the inside of the conveying member on the downstream side in the conveying direction of the transfer unit. And a spacer member that is provided on a surface of the conductive fiber member that faces the conveying member and that contacts the conveying member. The spacer member is uneven in a direction perpendicular to the conveying direction of the transfer material. in continuous sawtooth shape It, the convex portion of the spacer member is characterized in that it extends to the tip of the downstream side of the transfer material in the conductive fiber member.

In the invention having the above-described configuration, in the image forming apparatus that includes the endless belt-shaped conveyance member and forms a color image, excess charge is removed from the back side of the endless belt-shaped conveyance member by the neutralization unit, and the neutralization unit is configured by the spacer member. Since it is not in direct contact with the conveying member, it is possible to prevent excessive static elimination due to deterioration of the static eliminating means and back surface contamination of the conveying member. In other words, the serrated convex portion extends to the tip of the conductive fiber member and prevents contact between the paper and the conductive fiber member, while the presence of the concave portion can reduce the distance between the conductive fiber member and the paper. As a result, the static elimination effect can be enhanced.

According to a fourth aspect of the present invention, in the image forming apparatus, the spacer member is provided at a free end portion away from a support portion that supports the conductive fiber member .

In the invention having the above-described configuration, it is possible to prevent the static elimination unit pressed against the transfer material from being excessively pressed by the rigidity of the spacer member .

The image forming apparatus according to a fifth aspect is characterized in that the spacer member is provided over the entire width direction of the conductive fiber member .

In the invention of the above configuration, since the spacer member is provided over the entire width direction of the conductive fiber member, it is possible to prevent direct contact between the conductive fiber member and the transfer material while maintaining the charge eliminating effect on the entire transfer material. I can .

The image forming apparatus according to claim 6 includes a plurality of the spacer members in the transport direction, and the unevenness of the spacer members does not match in the transport direction .

In the invention having the above-described configuration, the interval between the conductive fiber members provided in the conveyance direction and the conveyance member is not constant in the conveyance direction, and therefore, it is possible to prevent a situation where a portion of insufficient static elimination or excessive static elimination occurs in the paper width direction. I can .

The image forming apparatus according to claim 7, wherein the spacer member has a thickness of 0.05 mm to 0.2 mm .

In the invention with the above configuration, the thickness of the spacer member, that is, the maximum value of the distance between the transfer material and the conductive fiber member is set to 0.2 mm or less, while maintaining the static elimination effect, and the minimum value is set to 0.05 mm, the strength is insufficient. In addition, direct contact between the transfer material and the conductive fiber member can be prevented .

The image forming apparatus according to an eighth aspect is characterized in that the spacer member has a thickness of 0.05 mm to 0.2 mm .

In the invention with the above configuration, the spacer member can be prevented from being charged by setting the volume resistance value of the spacer member to 10 6 Ω · cm or less .

  Since the present invention is configured as described above, an image forming apparatus having excellent transportability and image quality and being less likely to cause paper backside contamination can be obtained.

  FIG. 1 shows the structure of an image forming apparatus according to the first embodiment of the present invention.

  FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to Embodiment 1 of the present invention.

  The image forming apparatus is roughly divided into an image forming unit, an intermediate transfer device, and a final transfer body 40. The image forming unit includes four photosensitive drums 16Y, 16M, 16K, and 16C for yellow (Y), magenta (M), black (K), and cyan (C), and an exposure device and a development (not shown). Device.

  The intermediate transfer device includes a first intermediate transfer drum (IDT1) 14a that contacts the photosensitive drums 16Y and 16M, a first intermediate transfer drum (IDT1) 14b that contacts the photosensitive drums 16K and 16C, and the first of these two first transfer drums. And a second intermediate transfer drum (IDT2) 18 in contact with the intermediate transfer drums 16a and 16b.

  Further, a final transfer body (BTR) 20 is provided at a position facing the second intermediate transfer drum 18, and the paper P is nipped and conveyed between the second intermediate transfer drum 18 and the second intermediate transfer drum 18. The toner image 24 is transferred onto the paper P.

  When image formation is started, yellow, magenta, black, and cyan toner images are formed on the photosensitive drums 16Y to 16C, respectively.

  That is, the surface of each photosensitive drum 16 is negatively charged uniformly, and a laser beam corresponding to the output image is irradiated from the exposure device onto the surface of the photosensitive drum 16 after charging.

  Since the exposed portion is neutralized, an electrostatic latent image is formed on the surface of the photosensitive drum 16 due to a potential difference generated between the exposed portion and the unexposed portion, that is, the image portion and the non-image portion. It is formed.

  A developing device selectively applies negatively charged toner to the electrostatic latent image, and a toner image corresponding to the output image is formed on the surface of the photosensitive drum 16. That is, since the exposed portion is neutralized, the negatively charged toner 24 adheres to the image portion, and the unexposed portion is negatively charged, so the toner 24 does not adhere to the non-image portion. Become.

   Next, first, a magenta toner image is primarily transferred from the magenta photosensitive drum 16M to the first intermediate transfer drum 14a. Next, the yellow toner image is primarily transferred from the yellow photosensitive drum 16Y to the first intermediate transfer drum 14a, and is superimposed on the magenta toner image.

  On the other hand, similarly, a cyan toner image is primarily transferred from the cyan photosensitive drum 16C to the first intermediate transfer drum 14b. Next, the black toner image is primarily transferred from the black photosensitive drum 16K to the first intermediate transfer drum 14b.

  The primary-transferred magenta and yellow toner images 24 are secondarily transferred to the second intermediate transfer drum 18. On the other hand, the primary transferred black and cyan toner images 24 are also secondarily transferred to the second intermediate transfer drum 18, where the magenta and yellow toner images 24 that have been secondarily transferred first, and the black and cyan toner images 24 are transferred. The toner image 24 is overlaid, and a full-color toner image 24 and a black toner image 24 are formed on the second intermediate transfer drum 18.

  The secondary transfer full color toner image and black toner image reach the nip portion between the second intermediate transfer drum 18 and the final transfer body 20. In synchronization with this timing, the paper P as a recording medium is conveyed to the nip portion, and the full-color toner image 24 and the black toner image 24 are tertiary-transferred (final transfer) onto the paper P.

  Thereafter, the full color toner image 24 and the black toner image 24 are fixed on the paper P by the action of heat and pressure applied from the fixing device, and become a permanent image.

  At this time, the potential gradient of each member is controlled so as to have a potential gradient from minus to plus in the order of the photosensitive drum 16 → the first intermediate transfer drum 14 → the second intermediate transfer drum 18 → the final transfer body 20. Then, an image of negatively charged toner can be transferred from the photosensitive drum 16 toward the final transfer body 20.

  The paper P is nipped by the second intermediate transfer drum 18 by the final transfer body 20 and the toner image 24 is transferred, and then the paper P is peeled off from the final transfer body 20 by the peeling claw 22 and carried out.

  Further, there is provided a static elimination means 10 for contacting the back side (non-image forming surface) of the peeled paper P and removing excessive charging of the paper P. When the charge removing unit 10 comes into contact from the back side, the sheet P is removed from excessive charging, and the conveyance failure of the sheet JAM or the like is prevented.

  FIG. 2 shows a sheet peeling portion of the image forming apparatus according to the first embodiment of the present invention.

  As shown in FIG. 2, the sheet P is nipped between the final transfer body 20 and the secondary intermediate transfer drum 18, and the toner image 24 on the second intermediate transfer drum 18 is transferred.

  At this time, since the negatively charged toner 24 is adsorbed as described above, the paper P is also positively charged, and a force may act in the direction of wrapping around the final transfer body 20. 22 is provided to prevent the paper P from being wrapped around the final transfer body 20.

  However, even if the paper P is further conveyed, it may still cause JAM in a fixing device (not shown).

  However, if the charge removal is excessively strong, the electrostatic force attracting the toner image 24 to the paper P is insufficient, and the toner is peeled off to cause an image failure such as image flow. For this reason, the static elimination capability of the static elimination means 10 is required to be moderately strong.

  The neutralizing means 10 comprises conductive fibers 12, spacers 11, and holding members 13, and is urged so that the conductive fibers 12 are pressed against the conveyance path surface of the paper P with a certain pressure as shown in FIG. ing.

  A spacer 11 is provided on the side of the conductive fiber 12 that contacts the paper P so that the conductive fiber 12 does not directly contact the paper P, thereby preventing the conductive fiber 12 from fuzzing due to static electricity.

  Further, by providing the spacer 11, the distance between the conductive fiber 12 and the paper P can be maintained moderately, and it is possible to prevent failures such as the occurrence of image flow due to excessively high static elimination as described above.

  FIG. 3 shows a charge eliminating unit of the image forming apparatus according to the first embodiment of the present invention.

  As shown in FIG. 3, the static elimination means 10 consists of the conductive fiber 12, the spacer 11, and the holding member 13, and the spacer 11 has the serrated uneven | corrugated shape.

  That is, the convex portion 11b extends to the tip of the conductive fiber 12 and prevents contact between the paper P and the conductive fiber 12, while the presence of the concave portion 11a can reduce the distance between the conductive fiber 12 and the paper P. As a result, the static elimination effect can be enhanced.

  Further, since the spacer 11 is not bonded to the conductive fiber 12 at the portion 12 a where the conductive fiber 12 is fixed to the holding member 13, the rigidity of the spacer 11 does not hinder the free movement of the conductive fiber 12. .

  FIG. 4 shows a spacer used in the charge eliminating unit of the image forming apparatus according to the first embodiment of the present invention.

  4A is an overall view of the spacer 11, FIG. 4B is an enlarged view of an end portion, and FIG. 4C is a cross-sectional view. Numerical values in parentheses indicate dimensions (mm). However, this is merely an example, and the actual shape and dimensions are not limited thereto.

  FIG. 5 shows the structure of an image forming apparatus according to the second embodiment of the present invention.

  FIG. 5 is a schematic diagram showing an image forming apparatus according to Embodiment 2 of the present invention.

  The endless belt-like conveyance belt 30 driven by the driving roller 32 holds the sheet P by a method such as suction, transfers the toner image 24 from the photosensitive drums 16Y to 16K onto the sheet P, and then to a fixing device (not shown). Transport and fix as color image.

  At this time, neutralizing means 10Y to 10K for each color are provided not on the sheet P but on the back side of the conveying belt 30 and in the vicinity of the downstream side of the photosensitive drums 16Y to 16K. The neutralizing units 10Y to 10K prevent the sheet P and the conveyance belt 30 from being charged too much after the transfer of the toner 24 from the photosensitive drums 16Y to 16K, or cause deterioration of the conveyance property, or on the back side of the conveyance belt 30. In order to prevent the floating toner from adhering and becoming dirty, the conveying belt 30 is appropriately neutralized.

  FIG. 6 shows the structure of an image forming apparatus according to the third embodiment of the present invention.

  FIG. 6 is a schematic diagram showing an image forming apparatus according to Embodiment 3 of the present invention.

  The endless belt-like transfer belt 31 driven by the driving roller 32 is transferred with the toner image 24 from the photosensitive drums 16Y to 16K, and further transferred onto the paper P, thereby forming the toner image 24 on the paper P.

  At this time, neutralization means 10Y to 10K for each color are provided on the back side of the transfer belt 31 and in the vicinity of the downstream side of the photosensitive drums 16Y to 16K. The neutralizing means 10Y to 10K prevent the transfer belt 31 from being excessively charged after the transfer of the toner 24 from the photoconductive drums 16Y to 16K and causing deterioration of the transportability of the paper P, or on the back side of the transfer belt 31. In order to prevent the floating toner from adhering and becoming dirty, the transfer belt 31 is appropriately neutralized.

  FIG. 7 shows the arrangement of spacers according to the second and third embodiments of the present invention.

  As shown in FIG. 7, for example, the 10Y convex portion 11b and the 10M convex portion 11b 'are at different positions when viewed in the direction orthogonal to the paper transport direction, that is, in the paper width direction.

  This is because the portion where the convex portion 11b exists is the portion where the neutralization effect is the thinnest, so when the convex portion 11b overlaps at the same position in the paper conveyance direction, unevenness of the static elimination effect periodically occurs in the paper width direction. This is because streaks or the like flowing in the transport direction may occur.

  By changing the position of the convex portion 11b for each static elimination means, it is possible to prevent such unevenness of the static elimination effect.

  As described above, in the present invention, by providing the spacer 11, it is possible to prevent the conductive fibers 12 of the static elimination means 10 and the paper P, the conveyance belt 30 or the transfer belt 31 from coming into direct contact, and thus the conductive fibers can be prevented from fuzzing. However, a sufficient static elimination effect can be obtained.

1 is a cross-sectional view illustrating a structure of an image forming apparatus according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating a structure of an image forming apparatus according to a first embodiment of the present invention. It is a perspective view which shows the static elimination means which concerns on the 1st form of this invention. It is a top view which shows the spacer of the static elimination means which concerns on the 1st form of this invention. It is sectional drawing which shows the structure of the image forming apparatus which concerns on the 2nd form of this invention. It is sectional drawing which shows the structure of the image forming apparatus which concerns on the 3rd form of this invention. It is a perspective view which shows the spacer of the static elimination means which concerns on the 2nd form of this invention. It is a perspective view which shows the conventional static elimination means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Static elimination means 11 Spacer 12 Conductive fiber 18 2nd intermediate transfer drum 30 Conveying belt 31 Transfer belt

Claims (8)

At least one latent image carrier having a toner image formed on the surface;
Transfer means for transferring a toner image formed on the surface of the latent image carrier onto at least one intermediate transfer member or directly onto a transfer material;
An image forming apparatus provided with a charge eliminating unit that is provided downstream of the transfer unit in the transfer material conveyance direction and removes the electric charge accumulated in the transfer material,
The neutralizing means is a conductive fiber member urged in a direction facing and contacting the non-image forming surface of the transfer material on the downstream side in the transport direction;
A spacer member provided on a surface of the conductive fiber member facing the transfer material and contacting the transfer material ;
The spacer member has a serrated shape with concavities and convexities extending in a direction orthogonal to the transfer direction of the transfer material, and the convex portion of the spacer member is the tip of the conductive fiber member on the downstream side in the transfer direction of the transfer material An image forming apparatus, which extends to At least one latent image carrier having a toner image formed on the surface;
Transfer means for transferring a toner image formed on the surface of the latent image carrier onto at least one intermediate transfer member or directly onto a transfer material;
An image forming apparatus provided with a charge removing unit provided on a downstream side of the transfer unit in a transfer material conveyance direction and removing charges accumulated in the transfer material;
The static elimination means includes a spacer member that contacts the non-toner image transfer surface of the transfer material on the downstream side in the transport direction;
A conductive fiber member provided to face the non-toner image transfer surface of the transfer material via the spacer member ;
The spacer member has a serrated shape with concavities and convexities extending in a direction orthogonal to the transfer direction of the transfer material, and the convex portion of the spacer member is the tip of the conductive fiber member on the downstream side in the transfer direction of the transfer material An image forming apparatus, which extends to A plurality of latent image carriers each forming a different color toner image on the surface;
An endless belt-shaped conveying member for conveying a transfer material;
A plurality of transfer means for transferring a plurality of toner images formed on the surfaces of the plurality of latent image carriers onto the transfer material;
An image forming apparatus provided with a charge eliminating unit that is provided downstream of the transfer unit in the transfer material conveyance direction and removes the electric charge accumulated in the transfer material,
The neutralizing means is a conductive fiber member urged in a direction facing and in contact with the inside of the conveying member on the downstream side in the conveying direction of the transfer means,
A spacer member that is provided on a surface of the conductive fiber member that faces the conveying member and that contacts the conveying member;
The spacer member has a serrated shape with concavities and convexities extending in a direction orthogonal to the transfer direction of the transfer material, and the convex portion of the spacer member is the tip of the conductive fiber member on the downstream side in the transfer direction of the transfer material An image forming apparatus, which extends to The image forming apparatus according to claim 1 , wherein the spacer member is provided at a free end portion separated from a support portion that supports the conductive fiber member . The image forming apparatus according to claim 1, wherein the spacer member is provided over the entire width direction of the conductive fiber member . The image forming apparatus according to claim 3 , further comprising a plurality of the spacer members in a transport direction, wherein the unevenness of the spacer members does not coincide with each other in the transport direction . The image forming apparatus according to claim 1, wherein the spacer member has a thickness of 0.05 mm to 0.2 mm . The image forming apparatus according to claim 1, wherein a volume resistance value of the spacer member is 10 6 Ω · cm or less .

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